Updated on 2024/04/23

写真a

 
UESU, Yoshiaki
 
Affiliation
Faculty of Science and Engineering
Job title
Professor Emeritus
Degree
理学博士 ( 早稲田大学 )

Professional Memberships

  •  
     
     

    日本光学会

  •  
     
     

    日本結晶学会

  •  
     
     

    応用物理学会

  •  
     
     

    日本物理学会

Research Areas

  • Semiconductors, optical properties of condensed matter and atomic physics

Research Interests

  • 非線形光学

  • 相転移

  • 強誘電体

  • 固体物性I(光物性・半導体・誘電体)

  • 誘電体

  • Nonlinear optics

  • Phase transition

  • Ferroelectrics

  • Semiconductor & Dielectrics)

  • Solid-State Physics I (Optical Properties

▼display all

 

Books and Other Publications

  • Investigation of the two-dimensional polar molecular assembly using multi-purpose nonlinear optical microscope, , The Stefan University Press, 81-110 (2002).

    Ferroelectrics vol.2 , Series of Frontiers in Science and Technology  2002

Research Projects

  • 相転移

  • 非線形光学

  • 誘電体

  • Phase transition

  • Nonlinear Optics

  • Dielectrics

▼display all

Misc

  • SHG Microscope Observations of Domain Structures of Multiferroic BiFeO3 Single Crystal

    H. Matsuura, H. Yokota, R. Haumont, J. M. Kiat, Y. Uesu

    FERROELECTRICS   410   59 - 62  2011

     View Summary

    Temperature dependences of optical second harmonic generation (SHG) and light transmissivity are measured on a single crystal of multiferroic BiFeO3. SHG intensity exhibits a peak around the Neel temperature. The origin of this anomalous behavior could be attributed to rearrangements of ferroelectric micro-domain structures caused by spin-lattice coupling enhanced by ferroelectric order parameter.

    DOI

  • Three-Dimensional Visibility of Domain Structures Using the SHG Interference Microscope

    Junichi Kaneshiro, Yoshiaki Uesu

    FERROELECTRICS   412   32 - 37  2011

     View Summary

    Necessary conditions for the three-dimensional (3D) observation of polar domain structures using the second harmonic generation (SHG) interference microscope are examined. The essential point for the 3D observation is the use of an SHG tensor component with a negative wave-number misfit parameter Delta k(= k(2)-2k(1)) between the wave-number k(1) of the fundamental wave and k(2) of the SH wave. The origin of this phenomenon is explained with the Fourier transform technique. Delta k diagrams of the possible 3D observation are obtained for the sum-frequency generations in Mg doped LiNbO3 and BaTiO3.

    DOI CiNii

  • SHG Microscope Observations of Domain Structures of Multiferroic BiFeO3 Single Crystal

    H. Matsuura, H. Yokota, R. Haumont, J. M. Kiat, Y. Uesu

    FERROELECTRICS   410   59 - 62  2011

     View Summary

    Temperature dependences of optical second harmonic generation (SHG) and light transmissivity are measured on a single crystal of multiferroic BiFeO3. SHG intensity exhibits a peak around the Neel temperature. The origin of this anomalous behavior could be attributed to rearrangements of ferroelectric micro-domain structures caused by spin-lattice coupling enhanced by ferroelectric order parameter.

    DOI

  • Three-Dimensional Visibility of Domain Structures Using the SHG Interference Microscope

    Junichi Kaneshiro, Yoshiaki Uesu

    FERROELECTRICS   412   32 - 37  2011

     View Summary

    Necessary conditions for the three-dimensional (3D) observation of polar domain structures using the second harmonic generation (SHG) interference microscope are examined. The essential point for the 3D observation is the use of an SHG tensor component with a negative wave-number misfit parameter Delta k(= k(2)-2k(1)) between the wave-number k(1) of the fundamental wave and k(2) of the SH wave. The origin of this phenomenon is explained with the Fourier transform technique. Delta k diagrams of the possible 3D observation are obtained for the sum-frequency generations in Mg doped LiNbO3 and BaTiO3.

    DOI CiNii

  • Domain structure analysis of Pb ( Zn1/3 Nb2/3 ) O3 -9% PbTiO3 single crystals using optical second harmonic generation microscopy

    Junichi Kaneshiro, Yoshiaki Uesu

    Physical Review B - Condensed Matter and Materials Physics   82 ( 18 ) 184116  2010.11

     View Summary

    The domain structures of relaxor-ferroelectric Pb (Zn1/3 Nb 2/3) O3 -9% PbTiO3 (PZN-9PT) single crystals with a morphotropic phase boundary (MPB) composition are observed with a scanning second harmonic generation (SHG) microscope. Three-dimensional domain structures are obtained from sectional SH images along the axial direction. The domain structures are explained well by the strain compatibility theory that is based on the ferroelectric/ferroelastic phase transition of m 3̄ mFm (p) with the monoclinic space group Pm. The SHG images are divided into several parts, and the light-polarization dependence (PolD) at each site is calculated by minimizing the least-squares errors of the nonlinear susceptibilities. The PolDs are fitted well by theoretical formulas of the SH intensities for the Pm symmetry, and the two-dimensional map of the PolD coincides well with the corresponding SHG image of the domain structures. The monoclinic Pm symmetry at the MPB of PZN-9PT is determined at the optical diffraction limit of 460 nm. © 2010 The American Physical Society.

    DOI CiNii

  • Domain structure analysis of Pb ( Zn1/3 Nb2/3 ) O3 -9% PbTiO3 single crystals using optical second harmonic generation microscopy

    Junichi Kaneshiro, Yoshiaki Uesu

    Physical Review B - Condensed Matter and Materials Physics   82 ( 18 ) 184116  2010.11

     View Summary

    The domain structures of relaxor-ferroelectric Pb (Zn1/3 Nb 2/3) O3 -9% PbTiO3 (PZN-9PT) single crystals with a morphotropic phase boundary (MPB) composition are observed with a scanning second harmonic generation (SHG) microscope. Three-dimensional domain structures are obtained from sectional SH images along the axial direction. The domain structures are explained well by the strain compatibility theory that is based on the ferroelectric/ferroelastic phase transition of m 3̄ mFm (p) with the monoclinic space group Pm. The SHG images are divided into several parts, and the light-polarization dependence (PolD) at each site is calculated by minimizing the least-squares errors of the nonlinear susceptibilities. The PolDs are fitted well by theoretical formulas of the SH intensities for the Pm symmetry, and the two-dimensional map of the PolD coincides well with the corresponding SHG image of the domain structures. The monoclinic Pm symmetry at the MPB of PZN-9PT is determined at the optical diffraction limit of 460 nm. © 2010 The American Physical Society.

    DOI CiNii

  • Anomalous dielectric response in the dimer Mott insulator kappa-(BEDT-TTF)(2)Cu-2(CN)(3)

    Majed Abdel-Jawad, Ichiro Terasaki, Takahiko Sasaki, Naoki Yoneyama, Norio Kobayashi, Yoshiaki Uesu, Chisa Hotta

    PHYSICAL REVIEW B   82 ( 12 ) 125119  2010.09

     View Summary

    We have measured and analyzed the dielectric constant of the dimer Mott insulator kappa-(BEDT-TTF)(2)Cu-2(CN)(3), which is known as a playground for a spin-liquid state. Most unexpectedly, this particular organic salt has nontrivial charge degrees of freedom, being characterized by a relaxor-like dielectric relaxation below around 60 K. This is ascribed to the charge disproportionation within the dimer due to the intersite Coulomb repulsion. A possible microscopic model is suggested and discussed.

    DOI CiNii

  • Anomalous dielectric response in the dimer Mott insulator kappa-(BEDT-TTF)(2)Cu-2(CN)(3)

    Majed Abdel-Jawad, Ichiro Terasaki, Takahiko Sasaki, Naoki Yoneyama, Norio Kobayashi, Yoshiaki Uesu, Chisa Hotta

    PHYSICAL REVIEW B   82 ( 12 ) 125119  2010.09

     View Summary

    We have measured and analyzed the dielectric constant of the dimer Mott insulator kappa-(BEDT-TTF)(2)Cu-2(CN)(3), which is known as a playground for a spin-liquid state. Most unexpectedly, this particular organic salt has nontrivial charge degrees of freedom, being characterized by a relaxor-like dielectric relaxation below around 60 K. This is ascribed to the charge disproportionation within the dimer due to the intersite Coulomb repulsion. A possible microscopic model is suggested and discussed.

    DOI CiNii

  • Optical properties of transparent barium titanate nanoparticle/polymer hybrid synthesized from metal alkoxides

    Ken-ichi Mimura, Kosuke Hiramatsu, Makoto Moriya, Wataru Sakamoto, Satoshi Kawado, Yoshiaki Uesu, Toshinobu Yogo

    JOURNAL OF NANOPARTICLE RESEARCH   12 ( 5 ) 1933 - 1943  2010.06

     View Summary

    A transparent BaTiO(3) particle/polymer hybrid was synthesized from a Ba-Ti double alkoxide modified with an organic ligand and its refractive index and second harmonic generation were studied. BaTiO(3) particles modified with 2-vinyloxyethanol (ethylene glycol monovinyl ether, EGMVE) were polymerized with methyl methacrylate (MMA) yielding the transparent BaTiO(3) particle/poly MMA hybrid. X-ray photoelectron spectra indicated that the formation of chemical bonds between BaTiO(3) nanoparticles and the organic matrix. The refractive indexes of the hybrid films depended on the crystallite size of BaTiO(3) nanoparticles and the volume fractions of BaTiO(3) and polymer phases. The hybrid film synthesized at BaTiO(3)/8EGMVE/30H(2)O/PMMA revealed a refractive index of 1.65 at 589 nm with an Abbe number of 54. The hybrid film exhibited a second harmonic wave of 532 nm on irradiation with a fundamental wave of 1,064 nm.

    DOI CiNii

  • Optical properties of transparent barium titanate nanoparticle/polymer hybrid synthesized from metal alkoxides

    Ken-ichi Mimura, Kosuke Hiramatsu, Makoto Moriya, Wataru Sakamoto, Satoshi Kawado, Yoshiaki Uesu, Toshinobu Yogo

    JOURNAL OF NANOPARTICLE RESEARCH   12 ( 5 ) 1933 - 1943  2010.06

     View Summary

    A transparent BaTiO(3) particle/polymer hybrid was synthesized from a Ba-Ti double alkoxide modified with an organic ligand and its refractive index and second harmonic generation were studied. BaTiO(3) particles modified with 2-vinyloxyethanol (ethylene glycol monovinyl ether, EGMVE) were polymerized with methyl methacrylate (MMA) yielding the transparent BaTiO(3) particle/poly MMA hybrid. X-ray photoelectron spectra indicated that the formation of chemical bonds between BaTiO(3) nanoparticles and the organic matrix. The refractive indexes of the hybrid films depended on the crystallite size of BaTiO(3) nanoparticles and the volume fractions of BaTiO(3) and polymer phases. The hybrid film synthesized at BaTiO(3)/8EGMVE/30H(2)O/PMMA revealed a refractive index of 1.65 at 589 nm with an Abbe number of 54. The hybrid film exhibited a second harmonic wave of 532 nm on irradiation with a fundamental wave of 1,064 nm.

    DOI CiNii

  • Enhancing permittivity of ferroelectric superlattices via composition tuning

    N. A. Pertsev, P. -E. Janolin, J. -M. Kiat, Y. Uesu

    PHYSICAL REVIEW B   81 ( 14 ) 144118  2010.04

     View Summary

    A nonlinear thermodynamic theory is applied to strained ferroelectric superlattices and used to determine the dependence of superlattice permittivity on composition. To that end, spontaneous polarizations and field-induced polarization changes in the ferroelectric layers A and B with thicknesses t(A) and t(B) are calculated as a function of the volume fraction phi(A)=t(A)/(t(A)+ t(B)). The existence of a dielectric anomaly at a specific composition phi(A)* is predicted for the superlattices, where only one of ferroelectric layers has nonzero out-of-plane polarization in the uncoupled state. The theoretical predictions agree with the composition dependence of permittivity displayed by the Pb(Sc1/2Nb1/2)O-3/PbTiO3 superlattices grown on SrRuO3-covered SrTiO3.

    DOI CiNii

  • Polar clusters in impurity-doped quantum paraelectric K1-xLixTaO(3)

    Gregory Geneste, Jean-Michel Kiat, Hiroko Yokota, Yoshiaki Uesu, Florence Porcher

    PHYSICAL REVIEW B   81 ( 14 ) 144112  2010.04

     View Summary

    From density-functional calculations, we show that large off-center motions (approximate to 1.0 angstrom) of Li impurities in the KTaO3 matrix (studied at 3.7% concentration) create very anisotropic polar clusters oriented along the Li off-center dipole. The polarization induced by Li in the matrix decreases very sharply in the lateral directions so that polar clusters are only approximate to two lattice constants thick (one-dimensional or needlelike clusters). The polarization in such polar regions is mainly constituted by the displacements in the (highly polarizable) matrix rather than by the impurity itself. These results suggest that Li-doped potassium tantalate (3.7% concentration) is not ferroelectric at low temperature and rather behaves as a relaxor. These small polar zones around Li correlate at TB to form larger polar nanoregions, in which the matrix remains however nonpolar. This is confirmed by a low temperature neutron-diffraction analysis showing that the KTaO3 matrix remains paraelectric. Li-doped KTaO3 is an order-disorder system with a very deep local potential felt by the Li impurities (approximate to-200 meV). The energy barrier for Li hopping is estimated at 80-90 meV. An analytic expression for this local potential is provided, as well as a simple model describing the energetics of K1-xLixTaO3.

    DOI CiNii

  • Enhancing permittivity of ferroelectric superlattices via composition tuning

    N. A. Pertsev, P. -E. Janolin, J. -M. Kiat, Y. Uesu

    PHYSICAL REVIEW B   81 ( 14 ) 144118  2010.04

     View Summary

    A nonlinear thermodynamic theory is applied to strained ferroelectric superlattices and used to determine the dependence of superlattice permittivity on composition. To that end, spontaneous polarizations and field-induced polarization changes in the ferroelectric layers A and B with thicknesses t(A) and t(B) are calculated as a function of the volume fraction phi(A)=t(A)/(t(A)+ t(B)). The existence of a dielectric anomaly at a specific composition phi(A)* is predicted for the superlattices, where only one of ferroelectric layers has nonzero out-of-plane polarization in the uncoupled state. The theoretical predictions agree with the composition dependence of permittivity displayed by the Pb(Sc1/2Nb1/2)O-3/PbTiO3 superlattices grown on SrRuO3-covered SrTiO3.

    DOI CiNii

  • Polar clusters in impurity-doped quantum paraelectric K1-xLixTaO(3)

    Gregory Geneste, Jean-Michel Kiat, Hiroko Yokota, Yoshiaki Uesu, Florence Porcher

    PHYSICAL REVIEW B   81 ( 14 ) 144112  2010.04

     View Summary

    From density-functional calculations, we show that large off-center motions (approximate to 1.0 angstrom) of Li impurities in the KTaO3 matrix (studied at 3.7% concentration) create very anisotropic polar clusters oriented along the Li off-center dipole. The polarization induced by Li in the matrix decreases very sharply in the lateral directions so that polar clusters are only approximate to two lattice constants thick (one-dimensional or needlelike clusters). The polarization in such polar regions is mainly constituted by the displacements in the (highly polarizable) matrix rather than by the impurity itself. These results suggest that Li-doped potassium tantalate (3.7% concentration) is not ferroelectric at low temperature and rather behaves as a relaxor. These small polar zones around Li correlate at TB to form larger polar nanoregions, in which the matrix remains however nonpolar. This is confirmed by a low temperature neutron-diffraction analysis showing that the KTaO3 matrix remains paraelectric. Li-doped KTaO3 is an order-disorder system with a very deep local potential felt by the Li impurities (approximate to-200 meV). The energy barrier for Li hopping is estimated at 80-90 meV. An analytic expression for this local potential is provided, as well as a simple model describing the energetics of K1-xLixTaO3.

    DOI CiNii

  • Visibility of inverted domain structures using the second harmonic generation microscope: Comparison of interference and non-interference cases

    J. Kaneshiro, Y. Uesu, T. Fukui

    J. Opt. Soc. Am. B-Opt. Phys.   27 ( 5 ) 888  2010

    DOI CiNii

  • Dielectric Dispersion in KDP Crystals with Complex Organic and Inorganic Impurities

    S. V. Grabovsky, I. V. Shnaidshtein, B. A. Strukov, Y. Uesu, M. Fukunaga

    FERROELECTRICS   397   90 - 95  2010

     View Summary

    Dielectric properties of KH(2)PO(4) (KDP) crystals doped with complex organic (Amaranth, Chicago Sky Blue, Xylenol Orange) and inorganic (Potassium PentoChloroRuthenate) molecules were analyzed in the frequency range of 10 mHz-10 MHz. A noticeable dispersion in paraelectric phase at 30-80 degrees C is revealed. In some crystals with dyes the deviation of Cole-Cole diagrams from Debye-type relaxation is shown. Conductivity and activation energy of the conductivity mechanism at high temperature are determined.

    DOI CiNii

  • Optical and Nonlinear Optical Investigations of Phase Transition of Pb(Zn1/3Nb2/3)O-3-9% PbTiO3 Single Crystals

    J. Kaneshiro, Y. Uesu

    Jpn. J. Appl. Phys.   49   09ME02  2010

  • Syntheses of LiTaO3/LiNbO3 Super-Lattice Thin Films and Their Optical Properties

    Go Tsukahara, Yoshiaki Uesu

    FERROELECTRICS   406   31 - 34  2010

     View Summary

    LiTaO3(LT)/LiNbO3(LN) super-lattice thin films with different LT/LN ratios are fabricated on (0001) sapphire (-Al2O3) substrates using the pulsed laser deposition method. Well-defined X-ray super-lattice reflections are observed, and the SL period are calculated from these super-lattice positions, which coincide well with design ones estimated from the deposition velocities of LN and LT. X-ray -2 and in-plane phi-scans confirm the epitaxial growth of the films. Photon energy dependence of complex refractive indices n* of these super-lattice thin films are measured by a spectroscopic ellipsometer. The blue shift of n* with increase of LT ratio is observed.

    DOI

  • Visibility of inverted domain structures using the second harmonic generation microscope: Comparison of interference and non-interference cases

    J. Kaneshiro, Y. Uesu, T. Fukui

    J. Opt. Soc. Am. B-Opt. Phys.   27 ( 5 ) 888  2010

    DOI CiNii

  • Dielectric Dispersion in KDP Crystals with Complex Organic and Inorganic Impurities

    S. V. Grabovsky, I. V. Shnaidshtein, B. A. Strukov, Y. Uesu, M. Fukunaga

    FERROELECTRICS   397   90 - 95  2010

     View Summary

    Dielectric properties of KH(2)PO(4) (KDP) crystals doped with complex organic (Amaranth, Chicago Sky Blue, Xylenol Orange) and inorganic (Potassium PentoChloroRuthenate) molecules were analyzed in the frequency range of 10 mHz-10 MHz. A noticeable dispersion in paraelectric phase at 30-80 degrees C is revealed. In some crystals with dyes the deviation of Cole-Cole diagrams from Debye-type relaxation is shown. Conductivity and activation energy of the conductivity mechanism at high temperature are determined.

    DOI CiNii

  • Optical and Nonlinear Optical Investigations of Phase Transition of Pb(Zn1/3Nb2/3)O-3-9% PbTiO3 Single Crystals

    J. Kaneshiro, Y. Uesu

    Jpn. J. Appl. Phys.   49   09ME02  2010

  • Syntheses of LiTaO3/LiNbO3 Super-Lattice Thin Films and Their Optical Properties

    Go Tsukahara, Yoshiaki Uesu

    FERROELECTRICS   406   31 - 34  2010

     View Summary

    LiTaO3(LT)/LiNbO3(LN) super-lattice thin films with different LT/LN ratios are fabricated on (0001) sapphire (-Al2O3) substrates using the pulsed laser deposition method. Well-defined X-ray super-lattice reflections are observed, and the SL period are calculated from these super-lattice positions, which coincide well with design ones estimated from the deposition velocities of LN and LT. X-ray -2 and in-plane phi-scans confirm the epitaxial growth of the films. Photon energy dependence of complex refractive indices n* of these super-lattice thin films are measured by a spectroscopic ellipsometer. The blue shift of n* with increase of LT ratio is observed.

    DOI

  • Optical Study of the Accumulated Charge in the Amorphous InGaZnO4 Thin-Film Transistor

    Akira Kato, Yoshiaki Uesu, Takuro Katsufuji

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 9 ) 093706  2009.09

     View Summary

    Thin-film transistors (TFTs) with amorphous InGaZnO4 as a channel layer are known to exhibit high field-effect mobility. We studied the characteristic of the accumulated carriers in this TFT by optical spectroscopy and observed Drude absorption and oscillation in the transmittance spectrum of the channel region appearing with an applied gate voltage. The scattering rate of the carriers in the accumulation layers estimated from the optical spectrum is (h) over bar/tau(AL) = 0.19eV. and this small value is the origin of the high mobility of the TFT with amorphous InGaZnO4.

    DOI

  • Three-Dimensional Observations of LiNbO3 and LiTaO3 Quasi-Phase Matching Devices Using Transmission-Type Scanning Second-Harmonic Generation Interference Microscope

    Junichi Kaneshiro, Yoshiaki Uesu, Tatsuo Fukui

    JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 9 ) 09KF09  2009.09

     View Summary

    Periodically poled domain structures in stoichiometric LiNbO3 (PPSLN) and LiTaO3 (PPSLT) are observed using an optical second harmonic generation (SHG) interference microscope. Three-dimensional section images can be obtained in PPSLN using d(31) SHG tensor component. In PPSLT, the images of top and bottom surfaces are obtained using d(22) component. The difference in SHG images with and without interference is discussed. (C) 2009 The Japan Society of Applied Physics

    DOI

  • Optical Study of the Accumulated Charge in the Amorphous InGaZnO4 Thin-Film Transistor

    Akira Kato, Yoshiaki Uesu, Takuro Katsufuji

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   78 ( 9 ) 093706  2009.09

     View Summary

    Thin-film transistors (TFTs) with amorphous InGaZnO4 as a channel layer are known to exhibit high field-effect mobility. We studied the characteristic of the accumulated carriers in this TFT by optical spectroscopy and observed Drude absorption and oscillation in the transmittance spectrum of the channel region appearing with an applied gate voltage. The scattering rate of the carriers in the accumulation layers estimated from the optical spectrum is (h) over bar/tau(AL) = 0.19eV. and this small value is the origin of the high mobility of the TFT with amorphous InGaZnO4.

    DOI

  • Three-Dimensional Observations of LiNbO3 and LiTaO3 Quasi-Phase Matching Devices Using Transmission-Type Scanning Second-Harmonic Generation Interference Microscope

    Junichi Kaneshiro, Yoshiaki Uesu, Tatsuo Fukui

    JAPANESE JOURNAL OF APPLIED PHYSICS   48 ( 9 ) 09KF09  2009.09

     View Summary

    Periodically poled domain structures in stoichiometric LiNbO3 (PPSLN) and LiTaO3 (PPSLT) are observed using an optical second harmonic generation (SHG) interference microscope. Three-dimensional section images can be obtained in PPSLN using d(31) SHG tensor component. In PPSLT, the images of top and bottom surfaces are obtained using d(22) component. The difference in SHG images with and without interference is discussed. (C) 2009 The Japan Society of Applied Physics

    DOI

  • Second harmonic generation microscopic observations of a multiferroic BiFeO3 single crystal

    Hiroko Yokota, Raphael Haumont, Jean-Michel Kiat, Hiroto Matsuura, Yoshiaki Uesu

    APPLIED PHYSICS LETTERS   95 ( 8 ) 082904  2009.08

     View Summary

    Anisotropy of the optical second harmonic generation (SHG) in a multiferroic BiFeO3 single crystal is observed by an SHG microscope. Polarization dependences of SH intensities are measured in several polarization configurations of the incident and SH waves to determine the magnitude and sign of polar i-type SHG tensor components. To obtain proper values of these SHG tensors, the effects of the interference term and wave number mismatch are taken into account in these analyses. d(24) component is 15 times larger than d(32) and this result is essentially different from the thin film case.

    DOI CiNii

  • Second harmonic generation microscopic observations of a multiferroic BiFeO3 single crystal

    Hiroko Yokota, Raphael Haumont, Jean-Michel Kiat, Hiroto Matsuura, Yoshiaki Uesu

    APPLIED PHYSICS LETTERS   95 ( 8 ) 082904  2009.08

     View Summary

    Anisotropy of the optical second harmonic generation (SHG) in a multiferroic BiFeO3 single crystal is observed by an SHG microscope. Polarization dependences of SH intensities are measured in several polarization configurations of the incident and SH waves to determine the magnitude and sign of polar i-type SHG tensor components. To obtain proper values of these SHG tensors, the effects of the interference term and wave number mismatch are taken into account in these analyses. d(24) component is 15 times larger than d(32) and this result is essentially different from the thin film case.

    DOI CiNii

  • Direct observation of a repeatable change in electronic states with applied electric voltage pulses in the metal-insulator-metal structure

    K. Azumi, K. Aoyama, S. Asanuma, Y. Uesu, T. Katsufuji

    PHYSICAL REVIEW B   79 ( 12 ) 121101  2009.03

     View Summary

    By the microspectroscopic imaging of optical reflectivity for the La1-xSrxFeO3-delta thin film with indium-tin-oxide electrodes, we observed that the shape of the conducting area between two electrodes is reversibly varied with applied electric voltage pulses and that causes a repeatable change in the electrical resistance between the electrodes. These results can be explained by the oxygen-ion migration with applied electric field, which induces a variation in the distribution of the Fe4+ ions in the thin film.

    DOI CiNii

  • Direct observation of a repeatable change in electronic states with applied electric voltage pulses in the metal-insulator-metal structure

    K. Azumi, K. Aoyama, S. Asanuma, Y. Uesu, T. Katsufuji

    PHYSICAL REVIEW B   79 ( 12 ) 121101  2009.03

     View Summary

    By the microspectroscopic imaging of optical reflectivity for the La1-xSrxFeO3-delta thin film with indium-tin-oxide electrodes, we observed that the shape of the conducting area between two electrodes is reversibly varied with applied electric voltage pulses and that causes a repeatable change in the electrical resistance between the electrodes. These results can be explained by the oxygen-ion migration with applied electric field, which induces a variation in the distribution of the Fe4+ ions in the thin film.

    DOI CiNii

  • SHG Microscope Observations of Domain Structures in Multiferroic BiFeO3

    Hiroko Yokota, Raphael Haumont, Satoshi Kawado, Jean-Micheal Kiat, Charlotte Malibert, Yoshiaki Uesu

    FERROELECTRICS   379   401 - 406  2009

     View Summary

    Ferroelectric domain structures of BiFeO3 single crystals are observed using second harmonic generation and polarization microscopes. Anisotropy of SHG intensities is measured on (111)c and (110)c plates and analyzed by the Sapriel theory. The observed domains keep the same pattern from room temperature to above T-N of 643 K without essential change.

    DOI

  • Nonlinear Optical Properties and Ferroelectric Phase Transition of LaBGeO5

    Hiroko Yokota, Yoshiaki Uesu, Boris Strukov, Michael Glazer

    FERROELECTRICS   389   125 - 131  2009

     View Summary

    Optical second harmonic generation (SHG) and birefringence Delta n of ferroelectric LaBGeO5 are measured as a function of temperature. Using the Maker-Fringe method, magnitudes of SHG tensor components and coherence lengths are determined. From the symmetry analysis of d tensor components, the space group of the paraelectric phase is assigned to be non-centrosymmetric P3(1)2. The critical index of the order parameter is determined to be 0.5 from the birefringence measurement in the vicinity of T-C.

    DOI

  • Relaxor/Ferroelectric Super-Lattice Films Fabricated on the Single Lattice Scale

    Y. Uesu, S. Asanuma, C. Maliberet, J. M. Kiat

    FERROELECTRICS   390   130 - 135  2009

     View Summary

    Relaxor/ferroelectric super lattice films Pb(Sc1/2Nb1/2)O-3/PbTiO3 (PSN/PT) with different PT ratios are synthesized on the lattice cell scale by the pulsed laser deposition method. X-ray diffraction analyses reveal that fabricated and designed super-lattice (SL) periods coincide well within 6% error, and are uniform over thin film thickness of 100 nm. The lattice constant of PT in SL films shows an abrupt increase at a specific PT ratio of around 30%, which indicates the change in the a-axis to the c-axis domain configuration. The dielectric constant shows also the maximum at this PT ratio probably due to the dielectric anisotropy of PT, and it does not depend on the SL period.

    DOI

  • SHG Microscope Observations of Domain Structures in Multiferroic BiFeO3

    Hiroko Yokota, Raphael Haumont, Satoshi Kawado, Jean-Micheal Kiat, Charlotte Malibert, Yoshiaki Uesu

    FERROELECTRICS   379   401 - 406  2009

     View Summary

    Ferroelectric domain structures of BiFeO3 single crystals are observed using second harmonic generation and polarization microscopes. Anisotropy of SHG intensities is measured on (111)c and (110)c plates and analyzed by the Sapriel theory. The observed domains keep the same pattern from room temperature to above T-N of 643 K without essential change.

    DOI

  • Nonlinear Optical Properties and Ferroelectric Phase Transition of LaBGeO5

    Hiroko Yokota, Yoshiaki Uesu, Boris Strukov, Michael Glazer

    FERROELECTRICS   389   125 - 131  2009

     View Summary

    Optical second harmonic generation (SHG) and birefringence Delta n of ferroelectric LaBGeO5 are measured as a function of temperature. Using the Maker-Fringe method, magnitudes of SHG tensor components and coherence lengths are determined. From the symmetry analysis of d tensor components, the space group of the paraelectric phase is assigned to be non-centrosymmetric P3(1)2. The critical index of the order parameter is determined to be 0.5 from the birefringence measurement in the vicinity of T-C.

    DOI

  • Relaxor/Ferroelectric Super-Lattice Films Fabricated on the Single Lattice Scale

    Y. Uesu, S. Asanuma, C. Maliberet, J. M. Kiat

    FERROELECTRICS   390   130 - 135  2009

     View Summary

    Relaxor/ferroelectric super lattice films Pb(Sc1/2Nb1/2)O-3/PbTiO3 (PSN/PT) with different PT ratios are synthesized on the lattice cell scale by the pulsed laser deposition method. X-ray diffraction analyses reveal that fabricated and designed super-lattice (SL) periods coincide well within 6% error, and are uniform over thin film thickness of 100 nm. The lattice constant of PT in SL films shows an abrupt increase at a specific PT ratio of around 30%, which indicates the change in the a-axis to the c-axis domain configuration. The dielectric constant shows also the maximum at this PT ratio probably due to the dielectric anisotropy of PT, and it does not depend on the SL period.

    DOI

  • Phase transition in thin epitaxial ferroelectric films as derived from thermal measurements

    S. T. Davitadze, B. A. Strukov, D. V. Vysotskii, V. V. Lemanov, S. G. Shul'man, Y. Uesu, S. Asanuma

    PHYSICS OF THE SOLID STATE   50 ( 12 ) 2303 - 2306  2008.12

     View Summary

    The temperature dependence of the heat capacity of thin epitaxial films BaTiO(3)/MgO is studied by the dynamic 3 omega method in the thickness range 50-500 nm. It is revealed that the heat capacity exhibits diffuse anomalies due to phase transitions. The temperature of the ferroelectric phase transition T (C) increases with decreasing film thickness. The reasons for the strong diffuseness of the transition and the nonlinear dependence of the transition temperature on the film thickness are discussed.

    DOI

  • Phase transition in thin epitaxial ferroelectric films as derived from thermal measurements

    S. T. Davitadze, B. A. Strukov, D. V. Vysotskii, V. V. Lemanov, S. G. Shul'man, Y. Uesu, S. Asanuma

    PHYSICS OF THE SOLID STATE   50 ( 12 ) 2303 - 2306  2008.12

     View Summary

    The temperature dependence of the heat capacity of thin epitaxial films BaTiO(3)/MgO is studied by the dynamic 3 omega method in the thickness range 50-500 nm. It is revealed that the heat capacity exhibits diffuse anomalies due to phase transitions. The temperature of the ferroelectric phase transition T (C) increases with decreasing film thickness. The reasons for the strong diffuseness of the transition and the nonlinear dependence of the transition temperature on the film thickness are discussed.

    DOI

  • Three-dimensional observations of polar domain structures using a confocal second-harmonic generation interference microscope

    Junichi Kaneshiro, Satoshi Kawado, Hiroko Yokota, Yoshiaki Uesu, Tatsuo Fukui

    JOURNAL OF APPLIED PHYSICS   104 ( 5 ) 054112  2008.09

     View Summary

    The necessary conditions for nondestructive and three-dimensional (3D) observations of inverted polar domain structures using the second-harmonic generation interference microscope (SHGIM) are examined experimentally and theoretically using MgO doped congruent LiNbO3 and periodically poled (PP) MgO doped near stoichiometrical LiNbO3. The results can be explained well by the Boyd and Kleinman theory of strongly focused optical systems. To obtain clear 3D images of domain structures by SHGIM, the sign of the wave number Delta k offset of the fundamental and SH waves should be negative and the SHG tensor components d(31) should be used for both samples when they are observed with a wavelength of 1064 nm at room temperature. Under these conditions, 3D PP domain structures are clearly revealed by SHGIM. General conditions for the 3D visualization of polar domain structures are discussed for the cases of sum-frequency and difference-frequency generations. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Three-dimensional observations of polar domain structures using a confocal second-harmonic generation interference microscope

    Junichi Kaneshiro, Satoshi Kawado, Hiroko Yokota, Yoshiaki Uesu, Tatsuo Fukui

    JOURNAL OF APPLIED PHYSICS   104 ( 5 ) 054112  2008.09

     View Summary

    The necessary conditions for nondestructive and three-dimensional (3D) observations of inverted polar domain structures using the second-harmonic generation interference microscope (SHGIM) are examined experimentally and theoretically using MgO doped congruent LiNbO3 and periodically poled (PP) MgO doped near stoichiometrical LiNbO3. The results can be explained well by the Boyd and Kleinman theory of strongly focused optical systems. To obtain clear 3D images of domain structures by SHGIM, the sign of the wave number Delta k offset of the fundamental and SH waves should be negative and the SHG tensor components d(31) should be used for both samples when they are observed with a wavelength of 1064 nm at room temperature. Under these conditions, 3D PP domain structures are clearly revealed by SHGIM. General conditions for the 3D visualization of polar domain structures are discussed for the cases of sum-frequency and difference-frequency generations. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Structural and dielectric characterizations of relaxor/ferroelectric superlattice films Pb(Sc(1/2)Nb(1/2))O(3)/PbTiO(3) fabricated on a single-lattice scale

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    JOURNAL OF APPLIED PHYSICS   103 ( 9 ) 094106  2008.05

     View Summary

    Relaxor/ferroelectric superlattice (SL) films Pb(Sc(1/2)Nb(1/2))O(3)(PSN)/PbTiO(3)(PT) with nine different PT concentrations x are fabricated by a pulsed laser deposition method, which keeps the total film thickness at 100 nm. The structure of the SL films is examined by out-of-plane and in-plane x-ray diffractions. All films are epitaxial and their SL structures are coherent over the whole sample. SL reflections up to the fourth order are observed. Lattice constants of the PT and PSN layers in the SL are determined, and the PT lattice constant exhibits a marked increase at x(m)=32%. At this PT concentration, this phenomenon is due to a polarization reorientation from the a-axis oriented to the c-axis oriented domain. The complex dielectric constants of all samples are measured in the frequency region from 1 to 10(6) Hz, and the intrinsic dielectric constant epsilon of the SL is derived by an analysis using the equivalent electric circuit model. epsilon takes the maximum at x(m). The possible origin of this peculiar phenomenon is discussed. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Structural and dielectric characterizations of relaxor/ferroelectric superlattice films Pb(Sc(1/2)Nb(1/2))O(3)/PbTiO(3) fabricated on a single-lattice scale

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    JOURNAL OF APPLIED PHYSICS   103 ( 9 ) 094106  2008.05

     View Summary

    Relaxor/ferroelectric superlattice (SL) films Pb(Sc(1/2)Nb(1/2))O(3)(PSN)/PbTiO(3)(PT) with nine different PT concentrations x are fabricated by a pulsed laser deposition method, which keeps the total film thickness at 100 nm. The structure of the SL films is examined by out-of-plane and in-plane x-ray diffractions. All films are epitaxial and their SL structures are coherent over the whole sample. SL reflections up to the fourth order are observed. Lattice constants of the PT and PSN layers in the SL are determined, and the PT lattice constant exhibits a marked increase at x(m)=32%. At this PT concentration, this phenomenon is due to a polarization reorientation from the a-axis oriented to the c-axis oriented domain. The complex dielectric constants of all samples are measured in the frequency region from 1 to 10(6) Hz, and the intrinsic dielectric constant epsilon of the SL is derived by an analysis using the equivalent electric circuit model. epsilon takes the maximum at x(m). The possible origin of this peculiar phenomenon is discussed. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Temperature evolution of lattice strains in relaxor PbSc1/2Nb1/2O3 thin films

    Pierre-Eymeric Janolin, Jean-Michel Kiat, Charlotte Malibert, Shutaro Asanuma, Yoshiaki Uesu

    APPLIED PHYSICS LETTERS   92 ( 5 ) 052908  2008.02

     View Summary

    Temperature evolution of the lattice parameters of relaxor PbSc1/2Nb1/2O3 (PSN) thin films have been measured and compared to the evolution of bulk PSN. In PSN films, a room temperature tetragonal polar phase transforms at higher temperature into a nonpolar tetragonal phase. Critical and Burns temperatures, associated, respectively, to the onset of the ferroelectric phase and to the nucleation of polar nanoregions have been assigned from strong anomalies in the temperature evolution of the film. These complex behaviors are explained by a quantitative study of the strains lying in the film. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Critical behavior of K1-xLixTaO3 with the tri-critical concentration of Li under an electric field

    Hiroko Yokota, Yoshiaki Uesu

    Journal of the Physical Society of Japan   77 ( 2 ) 023713  2008.02

     View Summary

    Temperature dependences of the optical second harmonic generation in Li-doped KTaO3 (KLT) with different Li concentrations x are measured to determine the coefficients in the Landau-Devonshire free energy function. The result specifies the tri-critical Li concentration xc. Temperature dependences of the dielectric constant of KLT with Li concentrations nearly located at xc are also measured under dc bias fields and the result suggests that these compounds lie in close vicinity of the line of critical end points. The tertiary phase diagram (T, x, E) of KLT is disclosed from the experiments. ©2008 The Physical Society of Japan.

    DOI

  • Temperature evolution of lattice strains in relaxor PbSc1/2Nb1/2O3 thin films

    Pierre-Eymeric Janolin, Jean-Michel Kiat, Charlotte Malibert, Shutaro Asanuma, Yoshiaki Uesu

    APPLIED PHYSICS LETTERS   92 ( 5 ) 052908  2008.02

     View Summary

    Temperature evolution of the lattice parameters of relaxor PbSc1/2Nb1/2O3 (PSN) thin films have been measured and compared to the evolution of bulk PSN. In PSN films, a room temperature tetragonal polar phase transforms at higher temperature into a nonpolar tetragonal phase. Critical and Burns temperatures, associated, respectively, to the onset of the ferroelectric phase and to the nucleation of polar nanoregions have been assigned from strong anomalies in the temperature evolution of the film. These complex behaviors are explained by a quantitative study of the strains lying in the film. (C) 2008 American Institute of Physics.

    DOI CiNii

  • Critical behavior of K1-xLixTaO3 with the tri-critical concentration of Li under an electric field

    Hiroko Yokota, Yoshiaki Uesu

    Journal of the Physical Society of Japan   77 ( 2 ) 023713  2008.02

     View Summary

    Temperature dependences of the optical second harmonic generation in Li-doped KTaO3 (KLT) with different Li concentrations x are measured to determine the coefficients in the Landau-Devonshire free energy function. The result specifies the tri-critical Li concentration xc. Temperature dependences of the dielectric constant of KLT with Li concentrations nearly located at xc are also measured under dc bias fields and the result suggests that these compounds lie in close vicinity of the line of critical end points. The tertiary phase diagram (T, x, E) of KLT is disclosed from the experiments. ©2008 The Physical Society of Japan.

    DOI

  • 3D imaging of inverted domain structures by confocal SHG interference microscope

    Hiroko Yokota, Satoshi Kawado, Junichi Kaneshiro, Yoshiaki Uesu, Sunao Kurimura

    INTEGRATED FERROELECTRICS   98   156 - 160  2008

     View Summary

    A novel nonlinear optical interference microscope which enables us to take 3D images of ferroelectric domain structures is developed. This microscope is of a transmission type equipped with the confocal optical system, and exploits, as a probe, second harmonic waves generated in a sample by an incident laser beam. We apply the microscope to the observation of periodically poled domain structure in a LiTaO3 quasi-phase matching device.

    DOI

  • SHG Tomography for Domain Structure ObservationsAn Application to 3D Visualizations of Periodically Poled Domains

    S. Kawado, H. Yokota, J. Kaneshiro, Y. Uesu

    FERROELECTRICS   368   261 - 265  2008

     View Summary

    A novel confocal second harmonic generation (SHG) interference microscope with a transmission optical system is devised. This microscope is a kind of SHG tomography which provides us 3-dimensional images of heterogeneous structures in polar materials in non-destructive way. We apply successfully this microscope to observations of periodically poled domain structures in quasi-phase matching devices.

    DOI

  • Critical Point of Relaxor K1-xLixTaO3 Under an Electric Field

    Hiroko Yokota, Yoshiaki Uesu

    FERROELECTRICS   369   69 - 75  2008

     View Summary

    Optical second harmonic (SH) intensities and dielectric constants of Li doped KTaO3 are measured under an external electric field. Applying the Landau-Devonshire phenomenological theory to the temperature dependence of SH intensities, we find that the order of ferroelectric phase transition changes from 2nd to 1st with the increase of Li concentration. The dielectric measurement reveals that a critical behaviour similar to Pb(Mg1/3Nb2/3)O3-PbTiO3 is observed. Additionally, we find that the critical electric field depends on the frequency of electric field and the effect becomes conspicuous in lower frequencies in Li doped KTaO3.

    DOI

  • Phase Transitions in Ferroelectric Thin Films and Superlattices: Thermophysical Approach

    B. Strukov, S. Davitadze, V. Lemanov, S. Shulman, Y. Uesu, S. Asanuma, D. Schlom, A. Soukiassian

    FERROELECTRICS   370   57 - 64  2008

     View Summary

    It is shown that the information about thermophysical parameters of the nanostructured ferroelectrics is a useful supplement to the traditional x-ray and dielectric data. The results of the study of the temperature dependence of heat capacity of BaTiO3/MgO epitaxial thin films by dynamical 3 method for the thickness range 50-450 nm are presented. The blurred specific heat anomalies corresponding to the phase transitions were observed, and the temperature of the transitions increases with decreasing of film thickness compared with Tc in a bulk sample. The causes of the severe smearing of specific heat anomalies as well as pronounced nonlinearity of the dependence of the transition temperature on the film thickness are discussed. Specific heat data for ferroelectric superlattices (BaTiO3)n/(Sr TiO3)m/Sr TiO3 were obtained for the first time for the films with the average thicknesses near 100 nm.

    DOI

  • 3D imaging of inverted domain structures by confocal SHG interference microscope

    Hiroko Yokota, Satoshi Kawado, Junichi Kaneshiro, Yoshiaki Uesu, Sunao Kurimura

    INTEGRATED FERROELECTRICS   98   156 - 160  2008

     View Summary

    A novel nonlinear optical interference microscope which enables us to take 3D images of ferroelectric domain structures is developed. This microscope is of a transmission type equipped with the confocal optical system, and exploits, as a probe, second harmonic waves generated in a sample by an incident laser beam. We apply the microscope to the observation of periodically poled domain structure in a LiTaO3 quasi-phase matching device.

    DOI

  • SHG Tomography for Domain Structure ObservationsAn Application to 3D Visualizations of Periodically Poled Domains

    S. Kawado, H. Yokota, J. Kaneshiro, Y. Uesu

    FERROELECTRICS   368   261 - 265  2008

     View Summary

    A novel confocal second harmonic generation (SHG) interference microscope with a transmission optical system is devised. This microscope is a kind of SHG tomography which provides us 3-dimensional images of heterogeneous structures in polar materials in non-destructive way. We apply successfully this microscope to observations of periodically poled domain structures in quasi-phase matching devices.

    DOI

  • Critical point of relaxor K1-xLixTaO3 under an electric field

    Hiroko Yokota, Yoshiaki Uesu

    Ferroelectrics   369 ( 1 ) 69 - 75  2008

     View Summary

    Optical second harmonic (SH) intensities and dielectric constants of Li doped KTaO3 are measured under an external electric field. Applying the Landau-Devonshire phenomenological theory to the temperature dependence of SH intensities, we find that the order of ferroelectric phase transition changes from 2nd to 1st with the increase of Li concentration. The dielectric measurement reveals that a critical behaviour similar to Pb(Mg 1/3Nb2/3)O3-PbTiO3 is observed. Additionally, we find that the critical electric field depends on the frequency of electric field and the effect becomes conspicuous in lower frequencies in Li doped KTaO3.

    DOI

  • Phase Transitions in Ferroelectric Thin Films and Superlattices: Thermophysical Approach

    B. Strukov, S. Davitadze, V. Lemanov, S. Shulman, Y. Uesu, S. Asanuma, D. Schlom, A. Soukiassian

    FERROELECTRICS   370   57 - 64  2008

     View Summary

    It is shown that the information about thermophysical parameters of the nanostructured ferroelectrics is a useful supplement to the traditional x-ray and dielectric data. The results of the study of the temperature dependence of heat capacity of BaTiO3/MgO epitaxial thin films by dynamical 3 method for the thickness range 50-450 nm are presented. The blurred specific heat anomalies corresponding to the phase transitions were observed, and the temperature of the transitions increases with decreasing of film thickness compared with Tc in a bulk sample. The causes of the severe smearing of specific heat anomalies as well as pronounced nonlinearity of the dependence of the transition temperature on the film thickness are discussed. Specific heat data for ferroelectric superlattices (BaTiO3)n/(Sr TiO3)m/Sr TiO3 were obtained for the first time for the films with the average thicknesses near 100 nm.

    DOI

  • Three-dimensional observations of periodically poled domains in a LiTaO3 quasiphase matching crystal by second harmonic generation tomography

    Yoshiaki Uesu, Hiroko Yokota, Satoshi Kawado, Junichi Kaneshiro, Sunao Kurimura, Noritaka Kato

    APPLIED PHYSICS LETTERS   91 ( 18 ) 182904-182904-3  2007.10

     View Summary

    Second harmonic generation interference tomography which enables us to obtain three-dimensional images of ferroelectric antiparallel domain structures is devised. Periodically poled domains (PPDs) inside a LiTaO3 quasiphase matching crystal (QPM) are observed by this microscope. Section images perpendicular to the polar z axis show that the PPD structure is maintained throughout the top quarter of the sample but it starts to lose the periodic nature in the bottom half of the sample. Corresponding degradation of the QPM performance is observed along the z direction of the sample. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Three-dimensional observations of periodically poled domains in a LiTaO3 quasiphase matching crystal by second harmonic generation tomography

    Yoshiaki Uesu, Hiroko Yokota, Satoshi Kawado, Junichi Kaneshiro, Sunao Kurimura, Noritaka Kato

    APPLIED PHYSICS LETTERS   91 ( 18 ) 182904-182904-3  2007.10

     View Summary

    Second harmonic generation interference tomography which enables us to obtain three-dimensional images of ferroelectric antiparallel domain structures is devised. Periodically poled domains (PPDs) inside a LiTaO3 quasiphase matching crystal (QPM) are observed by this microscope. Section images perpendicular to the polar z axis show that the PPD structure is maintained throughout the top quarter of the sample but it starts to lose the periodic nature in the bottom half of the sample. Corresponding degradation of the QPM performance is observed along the z direction of the sample. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Non-ergodic Behavior of polarization growth in the quantum relaxor K1-xLixTaO3

    Hiroko Yokota, Yoshiaki Uesu

    JOURNAL OF THE KOREAN PHYSICAL SOCIETY   51 ( 2 ) 744 - 746  2007.08

     View Summary

    The quantum paraelectric KTaO3 doped with 3 % Li is investigated by using a second harmonic-generation microscope. A slow kinetics of the order parameter is observed under an electric field. At low temperatures below 30 K, the SH intensity doesn't grow in the laboratory time while around 40 K, the SH intensity increases steeply within 10 minutes, followed by a slow increase toward the equilibrium value. The phenomenon is related to three types of domains with different speeds of domain growth. The applicability of the theory proposed by Alberici-Kious et al. is also discussed.

  • Syntheses of relaxor/ferroelectric superlattice thin films Pb(Sc1/2Nb1/2)O-3/PbTiO3 and their dielectric properties

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    APPLIED PHYSICS LETTERS   90 ( 24 ) 242910  2007.06

     View Summary

    Superlattice (SL) thin films with different periods and composition ratios of Pb(Sc1/2Nb1/2)O-3 and PbTiO3 (PT), inside and outside the morphotropic phase boundary, are synthesized by a pulsed laser deposition method. High order SL reflections are observed by x-ray diffraction, from which the SL period and correlation length are determined. The coherency of the SL structure is found to extend over the whole film in the thinner films. A maximum dielectric constant of 1800 with a dielectric loss of 0.05 is obtained in the frequency range of 1-10(4) Hz for a SL with average composition of 25% of PT. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Origin of colossal dielectric response of CaCu3Ti4O12 studied by using CaTiO3/CaCu3Ti4O12/CaTiO3 multilayer thin films

    Masakazu Mitsugi, Shutaro Asanuma, Yoshiaki Uesu, Mamoru Fukunaga, Wataru Kobayashi, Ichiro Terasaki

    APPLIED PHYSICS LETTERS   90 ( 24 ) 242904  2007.06

     View Summary

    To elucidate the origin of the colossal dielectric response (CDR) of CaCu3Ti4O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTiO3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Syntheses of relaxor/ferroelectric superlattice thin films Pb(Sc1/2Nb1/2)O-3/PbTiO3 and their dielectric properties

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    APPLIED PHYSICS LETTERS   90 ( 24 ) 242910  2007.06

     View Summary

    Superlattice (SL) thin films with different periods and composition ratios of Pb(Sc1/2Nb1/2)O-3 and PbTiO3 (PT), inside and outside the morphotropic phase boundary, are synthesized by a pulsed laser deposition method. High order SL reflections are observed by x-ray diffraction, from which the SL period and correlation length are determined. The coherency of the SL structure is found to extend over the whole film in the thinner films. A maximum dielectric constant of 1800 with a dielectric loss of 0.05 is obtained in the frequency range of 1-10(4) Hz for a SL with average composition of 25% of PT. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Origin of colossal dielectric response of CaCu3Ti4O12 studied by using CaTiO3/CaCu3Ti4O12/CaTiO3 multilayer thin films

    Masakazu Mitsugi, Shutaro Asanuma, Yoshiaki Uesu, Mamoru Fukunaga, Wataru Kobayashi, Ichiro Terasaki

    APPLIED PHYSICS LETTERS   90 ( 24 ) 242904  2007.06

     View Summary

    To elucidate the origin of the colossal dielectric response (CDR) of CaCu3Ti4O12 (CCTO), multilayer thin films of CCTO interposed in insulating CaTiO3 (CTO) were synthesized using a pulsed laser deposition technique. The capacitance C of CTO/CCTO/CTO films with different layer thicknesses is measured. After removing the capacitance of CTO by extrapolating C to zero CTO thickness, the real part of dielectric constant of CCTO is estimated to be 329-435, which is much smaller than the reported value for CCTO thin films. This fact indicates that the CDR of CCTO is extrinsic and originates from an internal barrier layer capacitor. (c) 2007 American Institute of Physics.

    DOI CiNii

  • Second-harmonic generation and x-ray diffraction studies of the pretransitional region and polar phase in relaxor K(1-x) Lix Ta O3

    Hiroko Yokota, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    Physical Review B - Condensed Matter and Materials Physics   75 ( 18 ) 184113  2007.05

     View Summary

    Optical second-harmonic generation (SHG) observations and precise x-ray diffraction experiments have been performed on quantum paraelectrics KTa O3 (KTO) and relaxors K(1-x) Lix Ta O3 with x=3% (KLT-3) and 7% (KLT-7). It is found in KLT-3 and KLT-7 that a pretransitional region exists between two characteristic temperatures TB and Tp (&lt
    TB). The average symmetry of the region is tetragonal with a weak lattice deformation, but it is nonpolar on average. The temperature interval between TB and Tp is consistent with the interval in which neutron diffuse scatterings have been previously reported. TB is also found to align with the deviation temperature of the Curie-Weiss behavior of dielectric constant. These facts strongly suggest that polar nanoregions (PNRs) nucleate around TB and grow toward Tp. Below Tp, a larger deformation and a field-induced SH intensity start to develop, while no significant SHG appears in the zero-field-cooling (ZFC) process because of macroscopic inversion symmetry of the polydomain structure. The field-cooling (FC) process breaks the macroscopic inversion symmetry and the temperature dependence of SH intensity in field heating after FC coincides well with that of the tetragonality determined by x-ray diffraction experiments. The Landau-Devonshire phenomenological approach suggests that the ferroelectric phase transition at Tp is of first order and that it approaches the second-order transition with a decrease in the Li concentration. A marked increase of neutron-diffraction intensities below Tp, together with the disappearance of SHG intensity in a ZFC run, indicates that PNRs are transformed to ferroelectric microdomains at Tp. The microdomains become macroscopic below Tp in the FC process. In the lower-temperature region, nonergodic behavior was observed: The ZFC state cannot approach the thermodynamically equilibrium state under the electric field within finite time. © 2007 The American Physical Society.

    DOI CiNii

  • Second-harmonic generation and x-ray diffraction studies of the pretransitional region and polar phase in relaxor K(1-x) Lix Ta O3

    Hiroko Yokota, Yoshiaki Uesu, Charlotte Malibert, Jean-Michel Kiat

    Physical Review B - Condensed Matter and Materials Physics   75 ( 18 ) 184113  2007.05

     View Summary

    Optical second-harmonic generation (SHG) observations and precise x-ray diffraction experiments have been performed on quantum paraelectrics KTa O3 (KTO) and relaxors K(1-x) Lix Ta O3 with x=3% (KLT-3) and 7% (KLT-7). It is found in KLT-3 and KLT-7 that a pretransitional region exists between two characteristic temperatures TB and Tp (&lt
    TB). The average symmetry of the region is tetragonal with a weak lattice deformation, but it is nonpolar on average. The temperature interval between TB and Tp is consistent with the interval in which neutron diffuse scatterings have been previously reported. TB is also found to align with the deviation temperature of the Curie-Weiss behavior of dielectric constant. These facts strongly suggest that polar nanoregions (PNRs) nucleate around TB and grow toward Tp. Below Tp, a larger deformation and a field-induced SH intensity start to develop, while no significant SHG appears in the zero-field-cooling (ZFC) process because of macroscopic inversion symmetry of the polydomain structure. The field-cooling (FC) process breaks the macroscopic inversion symmetry and the temperature dependence of SH intensity in field heating after FC coincides well with that of the tetragonality determined by x-ray diffraction experiments. The Landau-Devonshire phenomenological approach suggests that the ferroelectric phase transition at Tp is of first order and that it approaches the second-order transition with a decrease in the Li concentration. A marked increase of neutron-diffraction intensities below Tp, together with the disappearance of SHG intensity in a ZFC run, indicates that PNRs are transformed to ferroelectric microdomains at Tp. The microdomains become macroscopic below Tp in the FC process. In the lower-temperature region, nonergodic behavior was observed: The ZFC state cannot approach the thermodynamically equilibrium state under the electric field within finite time. © 2007 The American Physical Society.

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  • CaCu3Ti4O12-type colossal dielectric relaxation in complex perovskite (Ba1-xLax)(Ti1-xCrx)O-3

    Mamoru Fukunaga, Yoshiaki Uesu, Guobao Li

    FERROELECTRICS   354   106 - 114  2007

     View Summary

    Dielectric constants of complex perovskite oxide (Ba1-xLax) (Ti1-xCrx)O-3 (BLTC) ceramics with 0.4 <= x <= 0.7 are measured, and a remarkable colossal dielectric relaxation which is quite similar to that of CaCu3Ti4O12 (CCTO) is found in higher temperature region above the ferroelectric phase transition. This kind of dielectric relaxation is successfully explained by an equivalent circuit model of a series of two R - C parallel circuits with temperature-dependent electrical conductivity and temperature-independent intrinsic dielectric constant. It is also found that the dc bias effect on the sample can distinguish this hetero-structure model and the proper Debye relaxation model of a homogeneous phase.

    DOI CiNii

  • Dielectric properties of CaCu3Ti4O12/CaTiO3 multilayer thin films synthesized by PLD method

    Masakazu Mitsugi, Mamoru Fukunaga, Shutaro Asanuma, Yoshiaki Uesu, Wataru Kobayashi, Ichiro Terasaki

    FERROELECTRICS   357   191 - 195  2007

     View Summary

    In order to elucidate the origin of the characteristic dielectric response of CaCu3Ti4O12 (CCTO), we synthesize c-axis oriented multilayer thin films composed of alternative layers of CCTO and an insulator CaTiO3 (CTO) using the Pulsed Laser Deposition (PLD) method and measure the capacitance of CTO/CCTO/CTO multilayer thin films with different thicknesses of CTO and CCTO layers. After removing the extrinsic electrode/CCTO boundary effect and the CCTO/CTO interface effect, the inherent dielectric constant of CCTO is determined.

    DOI

  • Optical properties of Li doped KTaO3 sing spectroscopic ellipsometer

    Hiroko Yokota, Jeremie Teyssier, Ronan Le Dantec, Yoshiaki Uesu, Jacques Bouillot

    FERROELECTRICS   355   171 - 175  2007

     View Summary

    Measurements of complex refractive indices n* = n - i kappa are performed on pure KTaO3 and K0.93Li0.07TaO3 single crystals by using a spectroscopic ellipsometer in temperature range from room temperature to 10 K. At room temperature, experimentally obtained complex dielectric constants epsilon* = epsilon(1) - i epsilon(2) of both crystals are analyzed by the classical Drude model. Temperature dependence of the imaginary pal-t epsilon 2 of K0.93Li0.07TaO3 shows a small but distinct change around 70 K. The origin of the anomalous behavior is discussed.

    DOI

  • Structural phase transition in two-dimensional crystallites of organic dye molecules formed on aqueous subphases

    Noritaka Kato, Ichiro Hirosawa, Masugu Sato, Naoshi Ikeda, Ken-Ichi Iimura, Yoshiaki Uesu

    Ferroelectrics   346   162 - 167  2007

     View Summary

    The 2D crystallites of polar organic dye molecules on an aqueous subphase exhibit a thermochromic phase transition. The visible absorption band of the crystallites depends on the temperature and the composition of the subphase. In-situ observations of the phase transition were carried out by a grazing incidence X-ray diffraction method. A shift and a split of the diffraction peaks were observed between the different phases, indicating a change in the molecular arrangement of the crystallites in their chromic transition.

    DOI CiNii

  • Structural and Dielectric Characterizations of Pb(Sc1/2Nb1/2)O-3-PbTiO3 Superlattice Thin Films

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean Michel Kiat

    FERROELECTRICS   347   174 - 178  2007

     View Summary

    Epitaxial Pb(Sc1/2Nb1/2)O-3 (PSN) and PbTiO3 (PT) superlattice thin films are processed on single-stepped SrTiO3 (001) substrates by the pulsed laser deposition (PLD) technique. SrRuO3 is deposited on the substrate as a bottom electrode layer for dielectric measurements. The orientation and structure of the films are determined by X-ray diffraction (XRD) method. Clear superlattice reflections are observed by XRD and the period of superlattice is calculated from difference of 2 theta of superlattice reflection. Real part of dielectric constant is about 350 at room temperature in the frequency range of 10(2)-10(5) Hz.

    DOI

  • Comparative Study of Phase Transitions in Polycrystalline and Epitaxial BaTiO(3) Thin Films by Specific Heat Measurements

    B. A. Strukov, S. T. Davitadze, V. V. Lemanov, S. G. Shulman, Y. Uesu, S. Asanuma

    FERROELECTRICS   347   179 - 185  2007

     View Summary

    The experimental data on the thermal properties of the nanostructured perovskite ferroelectrics are presented and analysed. The ability of the modified 3 omega method for specific heat measurements is discussed and illustrated by the thermal properties of the thin polycrystalline (BaTiO(3) on fused SiO(2), 50-1100 nm) and epitaxial (BaTiO(3) on MgO, 50-500 nm) films. The sharp decrease of the transition temperature, surplus entropy and spontaneous polarization were obtained for the polycrystalline films. The critical thickness and crystallite size are estimated for this case from the variation of both crystallite sizes at constant thickness and film thickness at constant crystallite size. The similarity of specific heat, phase transition excess entropy evolution in polycrystalline films and nanograined ceramics is revealed. The data on the specific heat of epitaxial films show the extremely diffused anomaly near 400 K, the phase transition has the weak tendency of shifting to higher temperatures with the decreasing of the film thickness. No anomalies were detected for the thinnest (50 nm) film up to 480 K.

    DOI

  • Is K(1-x)LixTaO3 a real relaxor?

    Y. Uesu, H. Yokota, J. M. Kiat, C. Malibert

    FERROELECTRICS   347   37 - 43  2007

     View Summary

    Li-doped KTaO3, K(1-x)LixTaO3 (KTL) has been reported to be a relaxor with an isovalent substitution of Li+ for K+. For confirming the idea, we performed second-harmonic generation microscopic observations, X-ray diffraction experiments and dielectric measurements of KTL with the critical concentration of Li (x = 3%). These reveal that an intermediate phase exists between 2 characteristic temperatures, T-d and T-p. The former corresponds to an elastic change accompanying small deformation and the latter to a dipolar change of the crystal. It is highly probable that the polar-nano regions appear below Td and transformed into ferroelectric domains at T-p. The present experiments support that KTL is a real relaxor.

    DOI

  • Recent Progress of SHG Interference Microscope and Its Applications

    Y. UESU, H. YOKOTA, S. KAWADO, N.KATO

    J.Korean Phys.Soc.   51 ( 2 ) 804 - 809  2007

  • Exremely slow kinetics of order papameter in relaxor KTaLiO3

    H.Yokota, Y.Uesu

    J.Phys.Condensed Matter   19   102201  2007

    DOI

  • Li concentration dependence of dielectric responses of quantum relaxor K1-xLixTaO3

    H. Yokota, A. Okada, I. Ishida, Y. Uesu

    Japanese Journal of Applied Physics   46 ( 10B ) 7167 - 7170  2007

    DOI CiNii

  • CaCu3Ti4O12-type colossal dielectric relaxation in complex perovskite (Ba1-xLax)(Ti1-xCrx)O-3

    Mamoru Fukunaga, Yoshiaki Uesu, Guobao Li

    FERROELECTRICS   354   106 - 114  2007

     View Summary

    Dielectric constants of complex perovskite oxide (Ba1-xLax) (Ti1-xCrx)O-3 (BLTC) ceramics with 0.4 <= x <= 0.7 are measured, and a remarkable colossal dielectric relaxation which is quite similar to that of CaCu3Ti4O12 (CCTO) is found in higher temperature region above the ferroelectric phase transition. This kind of dielectric relaxation is successfully explained by an equivalent circuit model of a series of two R - C parallel circuits with temperature-dependent electrical conductivity and temperature-independent intrinsic dielectric constant. It is also found that the dc bias effect on the sample can distinguish this hetero-structure model and the proper Debye relaxation model of a homogeneous phase.

    DOI CiNii

  • Non-ergodic Behavior of Polarization Growth in Quantum Relaxor K1-xLixTaO3

    H.Yokota, Y.Uesu

    J.Korean Phys.Soc   51 ( 2 ) 744 - 746  2007

  • Dielectric properties of CaCu3Ti4O12/CaTiO3 multilayer thin films synthesized by PLD method

    Masakazu Mitsugi, Mamoru Fukunaga, Shutaro Asanuma, Yoshiaki Uesu, Wataru Kobayashi, Ichiro Terasaki

    FERROELECTRICS   357   191 - 195  2007

     View Summary

    In order to elucidate the origin of the characteristic dielectric response of CaCu3Ti4O12 (CCTO), we synthesize c-axis oriented multilayer thin films composed of alternative layers of CCTO and an insulator CaTiO3 (CTO) using the Pulsed Laser Deposition (PLD) method and measure the capacitance of CTO/CCTO/CTO multilayer thin films with different thicknesses of CTO and CCTO layers. After removing the extrinsic electrode/CCTO boundary effect and the CCTO/CTO interface effect, the inherent dielectric constant of CCTO is determined.

    DOI

  • Optical properties of Li doped KTaO3 sing spectroscopic ellipsometer

    Hiroko Yokota, Jeremie Teyssier, Ronan Le Dantec, Yoshiaki Uesu, Jacques Bouillot

    FERROELECTRICS   355   171 - 175  2007

     View Summary

    Measurements of complex refractive indices n* = n - i kappa are performed on pure KTaO3 and K0.93Li0.07TaO3 single crystals by using a spectroscopic ellipsometer in temperature range from room temperature to 10 K. At room temperature, experimentally obtained complex dielectric constants epsilon* = epsilon(1) - i epsilon(2) of both crystals are analyzed by the classical Drude model. Temperature dependence of the imaginary pal-t epsilon 2 of K0.93Li0.07TaO3 shows a small but distinct change around 70 K. The origin of the anomalous behavior is discussed.

    DOI

  • Structural phase transition in two-dimensional crystallites of organic dye molecules formed on aqueous subphases

    Noritaka Kato, Ichiro Hirosawa, Masugu Sato, Naoshi Ikeda, Ken-Ichi Iimura, Yoshiaki Uesu

    Ferroelectrics   346   162 - 167  2007

     View Summary

    The 2D crystallites of polar organic dye molecules on an aqueous subphase exhibit a thermochromic phase transition. The visible absorption band of the crystallites depends on the temperature and the composition of the subphase. In-situ observations of the phase transition were carried out by a grazing incidence X-ray diffraction method. A shift and a split of the diffraction peaks were observed between the different phases, indicating a change in the molecular arrangement of the crystallites in their chromic transition.

    DOI CiNii

  • Structural and Dielectric Characterizations of Pb(Sc1/2Nb1/2)O-3-PbTiO3 Superlattice Thin Films

    Shutaro Asanuma, Yoshiaki Uesu, Charlotte Malibert, Jean Michel Kiat

    FERROELECTRICS   347   174 - 178  2007

     View Summary

    Epitaxial Pb(Sc1/2Nb1/2)O-3 (PSN) and PbTiO3 (PT) superlattice thin films are processed on single-stepped SrTiO3 (001) substrates by the pulsed laser deposition (PLD) technique. SrRuO3 is deposited on the substrate as a bottom electrode layer for dielectric measurements. The orientation and structure of the films are determined by X-ray diffraction (XRD) method. Clear superlattice reflections are observed by XRD and the period of superlattice is calculated from difference of 2 theta of superlattice reflection. Real part of dielectric constant is about 350 at room temperature in the frequency range of 10(2)-10(5) Hz.

    DOI

  • Comparative Study of Phase Transitions in Polycrystalline and Epitaxial BaTiO(3) Thin Films by Specific Heat Measurements

    B. A. Strukov, S. T. Davitadze, V. V. Lemanov, S. G. Shulman, Y. Uesu, S. Asanuma

    FERROELECTRICS   347   179 - 185  2007

     View Summary

    The experimental data on the thermal properties of the nanostructured perovskite ferroelectrics are presented and analysed. The ability of the modified 3 omega method for specific heat measurements is discussed and illustrated by the thermal properties of the thin polycrystalline (BaTiO(3) on fused SiO(2), 50-1100 nm) and epitaxial (BaTiO(3) on MgO, 50-500 nm) films. The sharp decrease of the transition temperature, surplus entropy and spontaneous polarization were obtained for the polycrystalline films. The critical thickness and crystallite size are estimated for this case from the variation of both crystallite sizes at constant thickness and film thickness at constant crystallite size. The similarity of specific heat, phase transition excess entropy evolution in polycrystalline films and nanograined ceramics is revealed. The data on the specific heat of epitaxial films show the extremely diffused anomaly near 400 K, the phase transition has the weak tendency of shifting to higher temperatures with the decreasing of the film thickness. No anomalies were detected for the thinnest (50 nm) film up to 480 K.

    DOI

  • Is K(1-x)LixTaO3 a real relaxor?

    Y. Uesu, H. Yokota, J. M. Kiat, C. Malibert

    FERROELECTRICS   347   37 - 43  2007

     View Summary

    Li-doped KTaO3, K(1-x)LixTaO3 (KTL) has been reported to be a relaxor with an isovalent substitution of Li+ for K+. For confirming the idea, we performed second-harmonic generation microscopic observations, X-ray diffraction experiments and dielectric measurements of KTL with the critical concentration of Li (x = 3%). These reveal that an intermediate phase exists between 2 characteristic temperatures, T-d and T-p. The former corresponds to an elastic change accompanying small deformation and the latter to a dipolar change of the crystal. It is highly probable that the polar-nano regions appear below Td and transformed into ferroelectric domains at T-p. The present experiments support that KTL is a real relaxor.

    DOI

  • Recent Progress of SHG Interference Microscope and Its Applications

    Y. UESU, H. YOKOTA, S. KAWADO, N.KATO

    J.Korean Phys.Soc.   51 ( 2 ) 804 - 809  2007

  • Exremely slow kinetics of order papameter in relaxor KTaLiO3

    H.Yokota, Y.Uesu

    J.Phys.Condensed Matter   19   102201  2007

    DOI

  • Li concentration dependence of dielectric responses of quantum relaxor K1-xLixTaO3

    H. Yokota, A. Okada, I. Ishida, Y. Uesu

    Japanese Journal of Applied Physics   46 ( 10B ) 7167 - 7170  2007

    DOI CiNii

  • Second-harmonic generation imaging of LiIO3/laponite nanocomposite waveguides

    Yannick Lambert, Ronan Le Dantec, Yannick Mugnier, Christine Galez, Jean-Claude Plenet, Jacques Bouillot, Hiromitsu Hayakawa, Yoshiaki Uesu

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 9B ) 7525 - 7530  2006.09

     View Summary

    We have developed LiIO3/laponite nanocomposite thin films to form waveguides with quadratic nonlinear optical properties. The films are dip-coated and annealed to induce LiIO3 crystallisation within the laponite matrix. LilO(3) nanocrystal orientation can be controlled using an electric field during the annealing process. In this article we perform the characterisations of the nanocomposite films through m-line spectroscopy and second harmonic generation microscopy (SHGM). Both refractive indexes deduced from m-line spectra and the SHG signal are shown to depend on the nanocrystal orientation distribution, and a relationship between the optical properties and microscopic structure of the films is developed.

    DOI CiNii

  • Second-harmonic generation imaging of LiIO3/laponite nanocomposite waveguides

    Yannick Lambert, Ronan Le Dantec, Yannick Mugnier, Christine Galez, Jean-Claude Plenet, Jacques Bouillot, Hiromitsu Hayakawa, Yoshiaki Uesu

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 9B ) 7525 - 7530  2006.09

     View Summary

    We have developed LiIO3/laponite nanocomposite thin films to form waveguides with quadratic nonlinear optical properties. The films are dip-coated and annealed to induce LiIO3 crystallisation within the laponite matrix. LilO(3) nanocrystal orientation can be controlled using an electric field during the annealing process. In this article we perform the characterisations of the nanocomposite films through m-line spectroscopy and second harmonic generation microscopy (SHGM). Both refractive indexes deduced from m-line spectra and the SHG signal are shown to depend on the nanocrystal orientation distribution, and a relationship between the optical properties and microscopic structure of the films is developed.

    DOI CiNii

  • Electric-field-induced resistance switching universally observed in transition-metal-oxide thin films

    M Hamaguchi, K Aoyama, S Asanuma, Y Uesu, T Katsufuji

    APPLIED PHYSICS LETTERS   88 ( 14 ) 142508  2006.04

     View Summary

    We show that polarity-dependent, nonvolatile resistance switching by electric field occurs in the thin film of various transition-metal oxides in almost the same manner. This result indicates that, contrary to the general acceptance, perovskite manganite is by no means a special compound for this phenomenon. It is also suggested that the resistance switching is not dominated by a detailed electronic structure of each sample, but dominated by a more general origin, e.g., crystalline defect. (c) 2006 American Institute of Physics.

    DOI

  • Electric-field-induced resistance switching universally observed in transition-metal-oxide thin films

    M Hamaguchi, K Aoyama, S Asanuma, Y Uesu, T Katsufuji

    APPLIED PHYSICS LETTERS   88 ( 14 ) 142508  2006.04

     View Summary

    We show that polarity-dependent, nonvolatile resistance switching by electric field occurs in the thin film of various transition-metal oxides in almost the same manner. This result indicates that, contrary to the general acceptance, perovskite manganite is by no means a special compound for this phenomenon. It is also suggested that the resistance switching is not dominated by a detailed electronic structure of each sample, but dominated by a more general origin, e.g., crystalline defect. (c) 2006 American Institute of Physics.

    DOI

  • Observation of rotation of polarization in thin films of PSNーPT via a monoclinic phase

    R.Haumont, B.Dkhil, C.Malibert, J.M.Kiat, F.LeMarrec, S.Asanuma, Y.Uesu

    Japanese J.Applied Physics   45 ( 1 ) L42-L45  2006

    DOI

  • Recent Progress of SHG Interference Microscope and Its Applications

    Y.Uesu, H.Yokota, S.Kawado, N.Kato

    Japan-Korea Conference of Ferroelectricity    2006

  • Is Li-doped KTaO3 really relaxor?

    Y.Uesu, H.Yokota

    Japan-Russia-CIA-Baltic Symposium on Ferroelectricity    2006

  • Thermochromism of merocyanine J-aggregate monolayers on binary counterion subphases

    Noritaka Kato, Yuji Ikegami, Yoshiaki Uesu

    Transactions of the Materials Research Society of Japan, Vol 31, No 3   31 ( 3 ) 565 - 568  2006

     View Summary

    The thermochromism of the merocyanine J-aggregates was investigated using the binary counterion subphase containing Mg2+ and Sr2+ (Mg2+/Sr2+ subphase). The behaviors of the thermochromic transition on the Mg2+/Sr2+ subphase and that on the subphase containing Mg2+ and Cd2+ were compared, and the difference was discussed from the viewpoint of the hydrated ionic radii of the counterions.

  • Acueous dispersion of J-aggregates and J-aggregate doped bulk-gels prepared by the dispersion

    K.Yamamoto, N.Kato, Y.Uesu

    Trans.Materials Res.Soc.Jpn   31 ( 3 ) 569 - 571  2006

  • Observation of rotation of polarization in thin films of PSNーPT via a monoclinic phase

    R.Haumont, B.Dkhil, C.Malibert, J.M.Kiat, F.LeMarrec, S.Asanuma, Y.Uesu

    Japanese J.Applied Physics   45 ( 1 ) L42-L45  2006

    DOI

  • Recent Progress of SHG Interference Microscope and Its Applications

    Y.Uesu, H.Yokota, S.Kawado, N.Kato

    Japan-Korea Conference of Ferroelectricity    2006

  • Is Li-doped KTaO3 really relaxor?

    Y.Uesu, H.Yokota

    Japan-Russia-CIA-Baltic Symposium on Ferroelectricity    2006

  • Thermochromism of merocyanine J-aggregate monolayers on binary counterion subphases

    Noritaka Kato, Yuji Ikegami, Yoshiaki Uesu

    Transactions of the Materials Research Society of Japan, Vol 31, No 3   31 ( 3 ) 565 - 568  2006

     View Summary

    The thermochromism of the merocyanine J-aggregates was investigated using the binary counterion subphase containing Mg2+ and Sr2+ (Mg2+/Sr2+ subphase). The behaviors of the thermochromic transition on the Mg2+/Sr2+ subphase and that on the subphase containing Mg2+ and Cd2+ were compared, and the difference was discussed from the viewpoint of the hydrated ionic radii of the counterions.

  • Acueous dispersion of J-aggregates and J-aggregate doped bulk-gels prepared by the dispersion

    K.Yamamoto, N.Kato, Y.Uesu

    Trans.Materials Res.Soc.Jpn   31 ( 3 ) 569 - 571  2006

  • Second-harmonic-generation microscopic observations of polar state in Li-doped KTaO3 under an electric field

    H Yokota, T Oyama, Y Uesu

    PHYSICAL REVIEW B   72 ( 14 ) 144103  2005.10

     View Summary

    Incipient ferroelectric KTaO3 with off-center Li impurity of the critical concentration of 2.8 mol % was investigated in order to clarify the dipole state under electric field. Using optical second-harmonic generation (SHG) microscope, we observed a marked history dependence of SHG intensity through zero-field cooling (ZFC), zero-field heating (ZFH), field heating after ZFC (FH/ZFC), and FH after field cooling (FH/FC). These show different paths with respect to temperature: In the ZFC/ZFH process, weak SHG was observed at low temperature, while in the FH/ZFC process, relatively high SHG appears in a limited temperature range below T-F depending on the field strength, and in the FC and FH/FC processes, the SHG exhibits ferroelectriclike temperature dependence: it appears at the freezing temperature of 50 K, increases with decreasing temperature, and has a tendency of saturation. These experimental results strongly suggest that dipole glass state or polar nanoclusters which gradually freezes with decreasing temperature is transformed into a semimacroscopic polar state under the electric field. However at sufficiently low temperature, the freezing is so strong that the electric field cannot enlarge the polar clusters. These experimental results show that the polar nanocluster model similar to relaxors would be more relevant in KTaO3 doped with the critical concentration of Li. Further experiments on the anisotropy of SHG determine that the average symmetry of the field-induced polar phase is tetragonal 4 mm or 4. The tetragonality is also confirmed by the x-ray diffraction measurement.

    DOI

  • Second-harmonic-generation microscopic observations of polar state in Li-doped KTaO3 under an electric field

    H Yokota, T Oyama, Y Uesu

    PHYSICAL REVIEW B   72 ( 14 ) 144103  2005.10

     View Summary

    Incipient ferroelectric KTaO3 with off-center Li impurity of the critical concentration of 2.8 mol % was investigated in order to clarify the dipole state under electric field. Using optical second-harmonic generation (SHG) microscope, we observed a marked history dependence of SHG intensity through zero-field cooling (ZFC), zero-field heating (ZFH), field heating after ZFC (FH/ZFC), and FH after field cooling (FH/FC). These show different paths with respect to temperature: In the ZFC/ZFH process, weak SHG was observed at low temperature, while in the FH/ZFC process, relatively high SHG appears in a limited temperature range below T-F depending on the field strength, and in the FC and FH/FC processes, the SHG exhibits ferroelectriclike temperature dependence: it appears at the freezing temperature of 50 K, increases with decreasing temperature, and has a tendency of saturation. These experimental results strongly suggest that dipole glass state or polar nanoclusters which gradually freezes with decreasing temperature is transformed into a semimacroscopic polar state under the electric field. However at sufficiently low temperature, the freezing is so strong that the electric field cannot enlarge the polar clusters. These experimental results show that the polar nanocluster model similar to relaxors would be more relevant in KTaO3 doped with the critical concentration of Li. Further experiments on the anisotropy of SHG determine that the average symmetry of the field-induced polar phase is tetragonal 4 mm or 4. The tetragonality is also confirmed by the x-ray diffraction measurement.

    DOI

  • Apparent colossal dielectric relaxation in SrTiO3 at high temperature

    M Fukunaga, Y Uesu, W Kobayashi, Terasaki, I

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 9B ) 7141 - 7143  2005.09

     View Summary

    Complex dielectric constants of SrTiO3 ceramics and single crystals were measured in the temperature range of 303 K to 673 K and the frequency range of 100 mHz to 100 kHz. It was found that the ceramic sample exhibits a steplike colossal dielectric relaxation similar to the distorted perovskite CaCu3Ti4O12, while the single crystal exhibits a relaxor-like relaxation. Both features can be explained with a heterogeneous structure model.

    DOI CiNii

  • Apparent colossal dielectric relaxation in SrTiO3 at high temperature

    M Fukunaga, Y Uesu, W Kobayashi, Terasaki, I

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   44 ( 9B ) 7141 - 7143  2005.09

     View Summary

    Complex dielectric constants of SrTiO3 ceramics and single crystals were measured in the temperature range of 303 K to 673 K and the frequency range of 100 mHz to 100 kHz. It was found that the ceramic sample exhibits a steplike colossal dielectric relaxation similar to the distorted perovskite CaCu3Ti4O12, while the single crystal exhibits a relaxor-like relaxation. Both features can be explained with a heterogeneous structure model.

    DOI CiNii

  • Determination of a merocyanine J-aggregate structure and the significant contribution of the electric dipole interaction to the exciton band wavelength

    N Kato, K Yuasa, T Araki, Hirosawa, I, M Sato, N Ikeda, K Iimura, Y Uesu

    PHYSICAL REVIEW LETTERS   94 ( 13 ) 136404  2005.04

     View Summary

    The molecular alignment of a merocyanine (MC) J-aggregate monolayer at the air-water interface was determined by a grazing incidence x-ray diffraction method. The obtained molecular arrangement apparently shows that the conventional formula, which accounts only for the transition dipole interaction, is not sufficient to figure out the exciton band wavelength, suggesting the importance of the electric dipole (ED) interaction. We derived a simple formula for the ED interaction energy under an extended dipole approximation and clarified the ED contribution in the MC J aggregate.

    DOI

  • Determination of a merocyanine J-aggregate structure and the significant contribution of the electric dipole interaction to the exciton band wavelength

    N Kato, K Yuasa, T Araki, Hirosawa, I, M Sato, N Ikeda, K Iimura, Y Uesu

    PHYSICAL REVIEW LETTERS   94 ( 13 ) 136404  2005.04

     View Summary

    The molecular alignment of a merocyanine (MC) J-aggregate monolayer at the air-water interface was determined by a grazing incidence x-ray diffraction method. The obtained molecular arrangement apparently shows that the conventional formula, which accounts only for the transition dipole interaction, is not sufficient to figure out the exciton band wavelength, suggesting the importance of the electric dipole (ED) interaction. We derived a simple formula for the ED interaction energy under an extended dipole approximation and clarified the ED contribution in the MC J aggregate.

    DOI

  • Advances on researches of relaxors-Dynamics and physical properties of the intrinsic inhomogeneity of dielectrics

    上江洲由晃

    日本物理学会 春季年会   領域10、領域5、領域8合同  2005

  • Advances on researches of relaxors-Dynamics and physical properties of the intrinsic inhomogeneity of dielectrics

    上江洲由晃

    日本物理学会 春季年会   領域10、領域5、領域8合同  2005

  • Electric-pulse-induced reflectance change in the thin film of perovskite manganite

    K Aoyama, K Waku, A Asanuma, Y Uesu, T Katsufuji

    APPLIED PHYSICS LETTERS   85 ( 7 ) 1208 - 1210  2004.08

     View Summary

    We demonstrate a nonvolatile, reversible change of infrared reflectance from the thin film of perovskite manganite (Pr1-xCaxMnO3) by applying electric pulse. The result provides a possibility to use the electric-pulse-induced phenomena of this compound in optical devices. (C) 2004 American Institute of Physics.

    DOI CiNii

  • Electric-pulse-induced reflectance change in the thin film of perovskite manganite

    K Aoyama, K Waku, A Asanuma, Y Uesu, T Katsufuji

    APPLIED PHYSICS LETTERS   85 ( 7 ) 1208 - 1210  2004.08

     View Summary

    We demonstrate a nonvolatile, reversible change of infrared reflectance from the thin film of perovskite manganite (Pr1-xCaxMnO3) by applying electric pulse. The result provides a possibility to use the electric-pulse-induced phenomena of this compound in optical devices. (C) 2004 American Institute of Physics.

    DOI CiNii

  • Phase transition and random-field induced domain wall response in quantum ferroelectrics (SrTiO3)-O-18: review and perspective

    M Itoh, T Yagi, Y Uesu, W Kleemann, R Blinc

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   5 ( 4 ) 417 - 423  2004.07

    Book review, literature introduction, etc.  

     View Summary

    The oxygen isotope exchange of O-16 by O-18 in SrTiO3 causes a drastic change from paraelectric to ferroelectric, due to the suppression of quantum fluctuation. The phase transition and origin of the huge domain wall response were evaluated by dielectric, magnetic (NMR), and optical measurements (SHG, light scattering). The results obtained corroborate (1) smeared ferroelectric transition at T-c due to quenched random field, (2) a quite large dielectric contribution from domain walls, (3) incomplete softening of the transverse optic mode, and (4) a large contribution from the relaxational mode to the phase transition. Quantitative explanations, given to individual results, may give hints to grasp the mechanism for the evolution of ferroelectricity, in which quantum fluctuation and random fields are dominant perturbations. Finally, some of the news studies on the SrTiO3 were also introduced. (C) 2004 Elsevier Ltd. All rights reserved.

    DOI CiNii

  • Phase transition and random-field induced domain wall response in quantum ferroelectrics (SrTiO3)-O-18: review and perspective

    M Itoh, T Yagi, Y Uesu, W Kleemann, R Blinc

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   5 ( 4 ) 417 - 423  2004.07

    Book review, literature introduction, etc.  

     View Summary

    The oxygen isotope exchange of O-16 by O-18 in SrTiO3 causes a drastic change from paraelectric to ferroelectric, due to the suppression of quantum fluctuation. The phase transition and origin of the huge domain wall response were evaluated by dielectric, magnetic (NMR), and optical measurements (SHG, light scattering). The results obtained corroborate (1) smeared ferroelectric transition at T-c due to quenched random field, (2) a quite large dielectric contribution from domain walls, (3) incomplete softening of the transverse optic mode, and (4) a large contribution from the relaxational mode to the phase transition. Quantitative explanations, given to individual results, may give hints to grasp the mechanism for the evolution of ferroelectricity, in which quantum fluctuation and random fields are dominant perturbations. Finally, some of the news studies on the SrTiO3 were also introduced. (C) 2004 Elsevier Ltd. All rights reserved.

    DOI CiNii

  • Polar order in quantum paraelectric (SrTiO3)-O-16 and (SrTiO3)-O-18 at low temperature

    Y Uesu, R Nakai, JM Kiat, C Menoret, M Itoh, T Kyomen

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 5 ) 1139 - 1142  2004.05

     View Summary

    Optical second-harmonic generation (SHG) in (SrTiO3)-O-16 (STO16) and (SrTiO3)-O-18 (STO18) was investigated using the SHG microscope. While no biased STO16 exhibits weak and almost temperature-independent SHG signals, a marked SHG is observed under the electric field in the quantum paraelectric region. In STO18, strong SHG signals appear spontaneously below 36 K. However, neutron and X-ray diffraction analyses indicate that no structural change appears at low temperature in STO18, or STO16 under the electric field. By taking into account the fact that the SHG is sensitive to the local polar order, the combined studies reveal that the long-range order of the polar phase does not develop on either crystal and is frozen in local regions.

    DOI

  • Polar order in quantum paraelectric (SrTiO3)-O-16 and (SrTiO3)-O-18 at low temperature

    Y Uesu, R Nakai, JM Kiat, C Menoret, M Itoh, T Kyomen

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   73 ( 5 ) 1139 - 1142  2004.05

     View Summary

    Optical second-harmonic generation (SHG) in (SrTiO3)-O-16 (STO16) and (SrTiO3)-O-18 (STO18) was investigated using the SHG microscope. While no biased STO16 exhibits weak and almost temperature-independent SHG signals, a marked SHG is observed under the electric field in the quantum paraelectric region. In STO18, strong SHG signals appear spontaneously below 36 K. However, neutron and X-ray diffraction analyses indicate that no structural change appears at low temperature in STO18, or STO16 under the electric field. By taking into account the fact that the SHG is sensitive to the local polar order, the combined studies reveal that the long-range order of the polar phase does not develop on either crystal and is frozen in local regions.

    DOI

  • Backward-wave four-wave mixing and coherent oscillation in CdF2 : Ga, Y

    Y Uesu, K Yasukawa, N Saito, S Odoulov, K Shcherbin, AI Ryskin, AS Shcheulin

    APPLIED PHYSICS B-LASERS AND OPTICS   78 ( 5 ) 601 - 605  2004.03

     View Summary

    Cadmium fluoride doped with Ga and Y is shown to be a suitable medium for backward-wave four-wave mixing with a grating decay time of a few seconds at room temperature. A 3-mm-thick sample ensures amplified phase-conjugate reflectivity and can therefore be used for building a coherent oscillator with a conventional mirror.

    DOI CiNii

  • Backward-wave four-wave mixing and coherent oscillation in CdF2 : Ga, Y

    Y Uesu, K Yasukawa, N Saito, S Odoulov, K Shcherbin, AI Ryskin, AS Shcheulin

    APPLIED PHYSICS B-LASERS AND OPTICS   78 ( 5 ) 601 - 605  2004.03

     View Summary

    Cadmium fluoride doped with Ga and Y is shown to be a suitable medium for backward-wave four-wave mixing with a grating decay time of a few seconds at room temperature. A 3-mm-thick sample ensures amplified phase-conjugate reflectivity and can therefore be used for building a coherent oscillator with a conventional mirror.

    DOI CiNii

  • 3D images of inverted domain structure in LiNbO3 using SHG interference microscope

    Y Uesu, H Shibata, S Suzuki, S Shimada

    FERROELECTRICS   304   929 - 933  2004

     View Summary

    A novel method of 3D visualization of 180-degree domain structures in ferroelectrics is proposed using the second harmonic generation (SHG) microscope. The essential part of the idea is to use 2D images with 4 phase differences, i.e., 0, pi/2, -pi/2 and pi, between SH waves generated in a sample and a homogeneous SHG plate. Inverted domain structures in MgO:LiNbO3 were successfully obtained: they grow in a wedgelike form both along the axial (y) and the lateral (z) directions of the sample under successive applications of pulsed electric field of 6 kV/mm.

    DOI

  • The structural and electric properties of BaTiO3-Ba(Fe1/2La1/2)O3 system

    G-B.Li, S-X.Liu, F.H.Liao, Y.Uesu e

    J.Solid State Chemistry   177 ( 4-5 ) 1695 - 1703  2004

    DOI

  • 3D images of inverted domain structure in LiNbO3 using SHG interference microscope

    Y.Uesu, H.Shibata, S.Suzuki, S.Shimada

    FERROELECTRICS   304   99 - 103  2004

    DOI

  • 多元系材料の新展開 ―材料の多元化・多次元により新しい機能の創成は可能か― 複合ペロブスカイト酸化物の巨大圧電効果

    上江洲由晃

    応用物理学会   学会予稿集  2004

  • TDGL simulation of slow kinetics observed in relaxor PMN

    Y.Uesu, K.Ishikawa

    European Physical Society - Condensed Matters Meeting   Prague  2004

  • Time evolutions of domain formation by the time-dependent Ginzburg-Landau equation

    Y.Uesu

    International Meeting of Ferroic Domains   Tsukuba  2004

  • 3D images of inverted domain structure in LiNbO3 using SHG interference microscope

    Y Uesu, H Shibata, S Suzuki, S Shimada

    FERROELECTRICS   304   929 - 933  2004

     View Summary

    A novel method of 3D visualization of 180-degree domain structures in ferroelectrics is proposed using the second harmonic generation (SHG) microscope. The essential part of the idea is to use 2D images with 4 phase differences, i.e., 0, pi/2, -pi/2 and pi, between SH waves generated in a sample and a homogeneous SHG plate. Inverted domain structures in MgO:LiNbO3 were successfully obtained: they grow in a wedgelike form both along the axial (y) and the lateral (z) directions of the sample under successive applications of pulsed electric field of 6 kV/mm.

    DOI

  • The structural and electric properties of BaTiO3-Ba(Fe1/2La1/2)O3 system

    G-B.Li, S-X.Liu, F.H.Liao, Y.Uesu e

    J.Solid State Chemistry   177 ( 4-5 ) 1695 - 1703  2004

    DOI

  • 3D images of inverted domain structure in LiNbO3 using SHG interference microscope

    Y.Uesu, H.Shibata, S.Suzuki, S.Shimada

    FERROELECTRICS   304   99 - 103  2004

    DOI

  • TDGL simulation of slow kinetics observed in relaxor PMN

    Y.Uesu, K.Ishikawa

    European Physical Society - Condensed Matters Meeting   Prague  2004

  • Time evolutions of domain formation by the time-dependent Ginzburg-Landau equation

    Y.Uesu

    International Meeting of Ferroic Domains   Tsukuba  2004

  • Dynamic grating recording in semiconductor CdF2 : Ga,Y

    Y Uesu, K Yasukawa, N Saito, S Itoh, S Odoulov, K Shcherbin, AI Ryskin

    JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS   20 ( 9 ) 1905 - 1911  2003.09

     View Summary

    Cadmium fluoride codoped with Ga and Y is characterized as a medium for phase grating recording. The dependence of the three-dimensional grating diffraction efficiency on the intensity of the recording light, on the polarization of the recording light, on the fringe contrast, and on the spatial frequency of the fringe was measured together with the dynamic characteristics (grating decay time and grating buildup time). The crystal behaved as a chi((3)) medium with its refractive-index change depending on linear intensity and with nearly exponential buildup-decay temporal characteristics for moderate intensities of the green recording light at room temperature. (C) 2003 Optical Society of America.

    DOI CiNii

  • Dynamic grating recording in semiconductor CdF2 : Ga,Y

    Y Uesu, K Yasukawa, N Saito, S Itoh, S Odoulov, K Shcherbin, AI Ryskin

    JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS   20 ( 9 ) 1905 - 1911  2003.09

     View Summary

    Cadmium fluoride codoped with Ga and Y is characterized as a medium for phase grating recording. The dependence of the three-dimensional grating diffraction efficiency on the intensity of the recording light, on the polarization of the recording light, on the fringe contrast, and on the spatial frequency of the fringe was measured together with the dynamic characteristics (grating decay time and grating buildup time). The crystal behaved as a chi((3)) medium with its refractive-index change depending on linear intensity and with nearly exponential buildup-decay temporal characteristics for moderate intensities of the green recording light at room temperature. (C) 2003 Optical Society of America.

    DOI CiNii

  • Compact and simple apparatus for measuring direct piezoelectricity

    M.Fukunaga, Y.Uesu

    Japanese J.Appl.Phys.   42 ( 9B ) 6115 - 6117  2003

    DOI CiNii

  • Study of 2D phase transition of polar organic dye molecules at the air-water interface by using granzing-incidence X-ray diffraction

    N Kato, Hirosawa, I, M Sato, N Ikeda, Y Uesu

    FERROELECTRICS   286   921 - 926  2003

     View Summary

    The grazing incidence X-ray diffraction from the 2D polar crystallites of organic dye molecules on an aqueous subphase was measured. The structure of the 2D crystallites shows a dependence on the subphase composition, and this dependence corresponds well to the results obtained from Langmuir-Blodgett films, which consist of the multilayer of the 2D crystallites deposited on the solid planar supports.

    DOI

  • Structure and dielectric properties of Ba(1-x)La(x)Ti (1-x)Cr(x)O3

    M.Fukunaga, Y.Uesu

    Ferroelectrics   286   801 - 806  2003

  • SHG microscopic studies on low temperature phase transitions of (SrTiO3)-O-16 and (SrTiO3)-O-18

    Y Uesu, R Nakai, N Kato, C Menoret, JM Kiat, M Itoh, M Narahashi, T Kyomen

    FERROELECTRICS   285   393 - 400  2003

     View Summary

    Marked field-induced second harmonic generation was observed in (SrTiO3)-O-16 at liquid. He temperature. The intensity decreased towards 35 K with the increase of temperature but it still remained significantly above 35 K and gradually diminished and vanished around 100 K. This indicates that ferroelectric nano-regions exist in higher temperature region and grow under electric field. On the other hand, O-18-replaced SrTiO3 ((SrTiO3)-O-18) exhibited SHG below 30 K without electric field and the intensity decreased steeply above the temperature. This corresponds to the appearance of ferroelectric phase. The point group of field-induced phase of (SrTiO3)-O-16 and ferroelectric phase of (SrTiO3)-O-18 is orthorhombic mm(2) with polar axis along the cubic {110} direction.

    DOI

  • Colosal response induced by hetero-structure fluctuation

    Y.Uesu, K.Ishikawa, Y.Yamada

    Trans. Materials Research Society of Japan   28 ( 1 ) 91 - 96  2003

  • Remarkable photorefractive properties of semiconductor with DX centers CdF2:Ga:Y

    Y.Uesu, Y.Yasukawa, N.Saito, S.Itoh, S.Odoulov, K.Shcherbin, R.Ryskin

    Trends in Optics and Photonics, Opt.Soc.Amer.   87  2003

  • Remarkable photorefractivity of semiconducter CdF2 with DX center

    Y.Uesu

    7th International Meeting of Photorefractive Effects, Devices and Materials   Nice, France  2003

  • SHG microscopic observation of SrTiO3 and O18-replaced SrTiO3 in quantum paraelectric regions

    Y.Uesu

    10th European Meeting of Ferroelectricity   Cambridge, England  2003

  • Colossal responses in quantum paraelectric region of SrTiO3

    Y. Uesu

    8th International Conference on Advanced Materials   Yokohama  2003

  • 可変コンデンサー及びこれを用いた圧電体の特性測定装置

    上江洲由晃, 福永守

    特願 2003-025362    2003

  • Compact and simple apparatus for measuring direct piezoelectricity

    M.Fukunaga, Y.Uesu

    Japanese J.Appl.Phys.   42 ( 9B ) 6115 - 6117  2003

     View Summary

    A new instrument for measuring piezoelectric coefficients has been developed. The principle of this instrument is simple, namely, applying a uniaxial stress to a sample and measuring the induced charge. The stress applied to the sample is measured as an electric signal. The main part of the instrument is shaped like a small probe with an electrode at the tip for measuring the charge, and piezoelectric coefficients can be measured easily and quickly by pressing the probe on samples by hand. The piezoelectric coefficient $d_{33}$ of ferroelectric Ba1-xLaxTi1-xCrxO3 ceramics were measured using the probe, and it is revealed that the compound shows a maximum $d_{33}$ of 70 pC/N when $x$ is approximately 0.014–0.018.

    DOI CiNii

  • Study of 2D phase transition of polar organic dye molecules at the air-water interface by using granzing-incidence X-ray diffraction

    N Kato, Hirosawa, I, M Sato, N Ikeda, Y Uesu

    FERROELECTRICS   286   921 - 926  2003

     View Summary

    The grazing incidence X-ray diffraction from the 2D polar crystallites of organic dye molecules on an aqueous subphase was measured. The structure of the 2D crystallites shows a dependence on the subphase composition, and this dependence corresponds well to the results obtained from Langmuir-Blodgett films, which consist of the multilayer of the 2D crystallites deposited on the solid planar supports.

    DOI

  • Structure and dielectric properties of Ba(1-x)La(x)Ti (1-x)Cr(x)O3

    M.Fukunaga, Y.Uesu

    Ferroelectrics   286   801 - 806  2003

  • SHG microscopic studies on low temperature phase transitions of (SrTiO3)-O-16 and (SrTiO3)-O-18

    Y Uesu, R Nakai, N Kato, C Menoret, JM Kiat, M Itoh, M Narahashi, T Kyomen

    FERROELECTRICS   285   393 - 400  2003

     View Summary

    Marked field-induced second harmonic generation was observed in (SrTiO3)-O-16 at liquid. He temperature. The intensity decreased towards 35 K with the increase of temperature but it still remained significantly above 35 K and gradually diminished and vanished around 100 K. This indicates that ferroelectric nano-regions exist in higher temperature region and grow under electric field. On the other hand, O-18-replaced SrTiO3 ((SrTiO3)-O-18) exhibited SHG below 30 K without electric field and the intensity decreased steeply above the temperature. This corresponds to the appearance of ferroelectric phase. The point group of field-induced phase of (SrTiO3)-O-16 and ferroelectric phase of (SrTiO3)-O-18 is orthorhombic mm(2) with polar axis along the cubic {110} direction.

    DOI

  • Colosal response induced by hetero-structure fluctuation

    Y.Uesu, K.Ishikawa, Y.Yamada

    Trans. Materials Research Society of Japan   28 ( 1 ) 91 - 96  2003

  • Remarkable photorefractive properties of semiconductor with DX centers CdF2:Ga:Y

    Y.Uesu, Y.Yasukawa, N.Saito, S.Itoh, S.Odoulov, K.Shcherbin, R.Ryskin

    Trends in Optics and Photonics, Opt.Soc.Amer.   87  2003

  • Remarkable photorefractivity of semiconducter CdF2 with DX center

    Y.Uesu

    7th International Meeting of Photorefractive Effects, Devices and Materials   Nice, France  2003

  • SHG microscopic observation of SrTiO3 and O18-replaced SrTiO3 in quantum paraelectric regions

    Y.Uesu

    10th European Meeting of Ferroelectricity   Cambridge, England  2003

  • Colossal responses in quantum paraelectric region of SrTiO3

    Y. Uesu

    8th International Conference on Advanced Materials   Yokohama  2003

  • Structure and conductivity of perovskites Sr1-xLaxTi1-xCrxO3

    GB Li, XJ Kuang, SJ Tian, FH Liao, XP Jing, Y Uesu, K Kohn

    JOURNAL OF SOLID STATE CHEMISTRY   165 ( 2 ) 381 - 392  2002.05

     View Summary

    The Sr1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 1) system was synthesized at 1500degreesC for about 60 h. Their structures were analyzed by the use of powder X-ray diffraction data and Rietveld analysis software GSAS (General Structure Analysis System). Three solid solutions are found: cubic solid solution Sr1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 0.168, space group Pm (3) over barm), rhombohedral solid solution Sr1-xLaxTi1-xCrxO3 (0.23 less than or equal to x less than or equal to 0.67, space group R (3) over barc) and orthorhombic solid solution Sr1-xLaxTi1-xCrxO3 (0.92 less than or equal to x less than or equal to 1, space group Pnma). The conductivities of this series were measured mainly from 25 to 450degreesC. It was found that this series changed from dielectric material SrTiO3 to semiconductor LaCrO3 continuously. The highest conductive sample was found to be Sr1-xLaxTi1-xCrxO3 with x = 0.92, whose conductivity at room temperature was about 5 X 10(-3) Omega(-1) cm(-1). (C) 2002 Elsevier Science (USA).

    DOI CiNii

  • Structure and conductivity of perovskites Sr1-xLaxTi1-xCrxO3

    GB Li, XJ Kuang, SJ Tian, FH Liao, XP Jing, Y Uesu, K Kohn

    JOURNAL OF SOLID STATE CHEMISTRY   165 ( 2 ) 381 - 392  2002.05

     View Summary

    The Sr1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 1) system was synthesized at 1500degreesC for about 60 h. Their structures were analyzed by the use of powder X-ray diffraction data and Rietveld analysis software GSAS (General Structure Analysis System). Three solid solutions are found: cubic solid solution Sr1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 0.168, space group Pm (3) over barm), rhombohedral solid solution Sr1-xLaxTi1-xCrxO3 (0.23 less than or equal to x less than or equal to 0.67, space group R (3) over barc) and orthorhombic solid solution Sr1-xLaxTi1-xCrxO3 (0.92 less than or equal to x less than or equal to 1, space group Pnma). The conductivities of this series were measured mainly from 25 to 450degreesC. It was found that this series changed from dielectric material SrTiO3 to semiconductor LaCrO3 continuously. The highest conductive sample was found to be Sr1-xLaxTi1-xCrxO3 with x = 0.92, whose conductivity at room temperature was about 5 X 10(-3) Omega(-1) cm(-1). (C) 2002 Elsevier Science (USA).

    DOI CiNii

  • Symmetry of high-piezoelectric Pb based complex perovskites at the morphotropic phase boundary: II. Theoretical treatment

    Y Yamada, Y Uesu, M Matsuda, K Fujishiro, DE Cox, B Noheda, G Shiranes

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   71 ( 3 ) 966 - 970  2002.03

     View Summary

    The structural characteristics of the perovskite-based ferroelectric Pb(Zn1/3Nb2/3)(1-x)TixO3 at the morphotropic phase boundary (MPB) region (x similar or equal to 0.09) have been analyzed. The analysis is based on the symmetry adapted free energy functions under the assumption that the total polarization and the unit cell volume are conserved during the transformations between various morphotropic phases. Overall features of the relationships between the observed lattice constants at various conditions have been consistently explained. The origin of the anomalous physical properties at MPB is discussed.

    DOI

  • Symmetry of high-piezoelectric Pb based complex perovskites at the morphotropic phase boundary: II. Theoretical treatment

    Y Yamada, Y Uesu, M Matsuda, K Fujishiro, DE Cox, B Noheda, G Shiranes

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   71 ( 3 ) 966 - 970  2002.03

     View Summary

    The structural characteristics of the perovskite-based ferroelectric Pb(Zn1/3Nb2/3)(1-x)TixO3 at the morphotropic phase boundary (MPB) region (x similar or equal to 0.09) have been analyzed. The analysis is based on the symmetry adapted free energy functions under the assumption that the total polarization and the unit cell volume are conserved during the transformations between various morphotropic phases. Overall features of the relationships between the observed lattice constants at various conditions have been consistently explained. The origin of the anomalous physical properties at MPB is discussed.

    DOI

  • Monoclinic structure of unpoled morphotropic high piezoelectric PMN-PT and PZN-PT compounds

    JM Kiat, Y Uesu, B Dkhil, M Matsuda, C Malibert, G Calvarin

    PHYSICAL REVIEW B   65 ( 6 ) 641061 - 641064  2002.02

     View Summary

    Evidences of a monoclinic phase in unpoled (PbMg1/3Nb2/3O3)(1-x)-(PbTiO3)(x) with x= 0.35 (PMN-PT 35%) and unpoled (PbZn1/3Nb2/3O3)(1-x)-(PbTiO3)(x) with x=0.09 (PZN-PT 9%) are presented from a neutron Rietveld analysis. This monoclinic phase is different from the phase recently evidenced by Noheda and co-workers in PhZr1-xTixO3 with x=0.48 [B. Noheda et al., Phys. Rev. B. 61, 8687 (2000)] but is identical to the phase observed in poled PZN-PT with x=0.08 [B. Noheda et al.. Phys. Rev. Lett. 86, 3891 (2001)] by the same authors. The structural resolutions allowed us to compare both structures and to deduce the direction and magnitude of polarization. In PMN-PT 35% and PZN-PT 9% this phase is characterized by a weak value of polarization, a strong deformation of oxygen polyhedra, and weak cationic shifts.

    DOI

  • Structural characterization of the complex perovskites Ba1-xLaxTi1-xCrxO3

    GB Li, Y Uesu, K Kohn

    JOURNAL OF SOLID STATE CHEMISTRY   164 ( 1 ) 98 - 105  2002.02

     View Summary

    The series Ba1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 1) was synthesized at 1400degreesC for about 60 h. Their structure was carefully analyzed by the use of powder X-ray diffraction and Rietveld analysis software GSAS (General Structure Analysis System). Four solid solutions are found in this series: tetragonal solid solution Ba1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 0.029), cubic solid solution Ba1-xLaxTi1-xCrxO3 (0.0365 less than or equal to x less than or equal to 0.600), rhombohedral solid solution Ba1-xLaxTi1-xCrxO3 (0.700 less than or equal to x less than or equal to 0.873), and orthorhombic solid solution Ba1-xLaxTi1-xCrxO3 (0.956 less than or equal to x less than or equal to 1). There are corresponding two-phase regions between the adjacent two solid solutions. The detailed lattice parameters are presented. The relationship between the lattice parameters and the composition of the solid solutions is developed. (C) 2002 Elsevier Science (USA).

    DOI CiNii

  • Monoclinic structure of unpoled morphotropic high piezoelectric PMN-PT and PZN-PT compounds

    JM Kiat, Y Uesu, B Dkhil, M Matsuda, C Malibert, G Calvarin

    PHYSICAL REVIEW B   65 ( 6 ) 641061 - 641064  2002.02

     View Summary

    Evidences of a monoclinic phase in unpoled (PbMg1/3Nb2/3O3)(1-x)-(PbTiO3)(x) with x= 0.35 (PMN-PT 35%) and unpoled (PbZn1/3Nb2/3O3)(1-x)-(PbTiO3)(x) with x=0.09 (PZN-PT 9%) are presented from a neutron Rietveld analysis. This monoclinic phase is different from the phase recently evidenced by Noheda and co-workers in PhZr1-xTixO3 with x=0.48 [B. Noheda et al., Phys. Rev. B. 61, 8687 (2000)] but is identical to the phase observed in poled PZN-PT with x=0.08 [B. Noheda et al.. Phys. Rev. Lett. 86, 3891 (2001)] by the same authors. The structural resolutions allowed us to compare both structures and to deduce the direction and magnitude of polarization. In PMN-PT 35% and PZN-PT 9% this phase is characterized by a weak value of polarization, a strong deformation of oxygen polyhedra, and weak cationic shifts.

    DOI

  • Structural characterization of the complex perovskites Ba1-xLaxTi1-xCrxO3

    GB Li, Y Uesu, K Kohn

    JOURNAL OF SOLID STATE CHEMISTRY   164 ( 1 ) 98 - 105  2002.02

     View Summary

    The series Ba1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 1) was synthesized at 1400degreesC for about 60 h. Their structure was carefully analyzed by the use of powder X-ray diffraction and Rietveld analysis software GSAS (General Structure Analysis System). Four solid solutions are found in this series: tetragonal solid solution Ba1-xLaxTi1-xCrxO3 (0 less than or equal to x less than or equal to 0.029), cubic solid solution Ba1-xLaxTi1-xCrxO3 (0.0365 less than or equal to x less than or equal to 0.600), rhombohedral solid solution Ba1-xLaxTi1-xCrxO3 (0.700 less than or equal to x less than or equal to 0.873), and orthorhombic solid solution Ba1-xLaxTi1-xCrxO3 (0.956 less than or equal to x less than or equal to 1). There are corresponding two-phase regions between the adjacent two solid solutions. The detailed lattice parameters are presented. The relationship between the lattice parameters and the composition of the solid solutions is developed. (C) 2002 Elsevier Science (USA).

    DOI CiNii

  • Structural and dielectric properties of Ni-doped and La-Cr-doped BaTiO3

    Jpn.J.Appl.Phys   41  2002

  • Structural phase transition in two-dimensional polar crystallites of organic dye molecules: In-plane X-ray diffraction analysis

    Ferroelectrics(Gordon & Breach)   269  2002

    DOI

  • Phase transitions and dielectric relaxation in dyeing KDP

    Ferroelectrics(Gordon&Breach)   267  2002

    DOI

  • Symmetry of high-piezoelectric Pb based complex perovskites at the morphotoropic phase boundary I. Neutron diffraction study on PZN/9PT, J. Phys. Soc. Japan, 960-965(2002).

    J. Phys. Soc. Japan   71, No.3, 966-970  2002

    DOI

  • Colossal Piezoelectric Effect in Complex Perovskite Oxides

    UESU Yoshiaki

    Butsuri   57 ( 9 ) 646 - 653  2002

     View Summary

    Revolutionary development has been recently found in piezoelectric materials. These are Pb-based complex perovskite oxides. In particular, the morphotropic boundary of relaxor and PbTiO3 complex exhibits huge piezoelectric response. The origin of the phenomenon is ascribed by the symmetry lowering which induces smooth polarization rotation. This report summarizes the experimental results and ab initio and phenomenological approaches to this problem.

    DOI CiNii

  • Colosal response induced bu hetero-structure fluctuation

    Y.Uesu

    Symposia of Material Research Society Japan    2002

  • SHG Microscopic studies on low temperature phase transitions of SrTiO3

    Y.Uesu

    7th RCBJ Symposium on Ferroelectricity, St.Peterburg, Russia    2002

  • Structural and dielectric properties of Ni-doped and La-Cr-doped BaTiO3

    Jpn.J.Appl.Phys   41  2002

  • Structural phase transition in two-dimensional polar crystallites of organic dye molecules: In-plane X-ray diffraction analysis

    Ferroelectrics(Gordon & Breach)   269  2002

    DOI

  • Phase transitions and dielectric relaxation in dyeing KDP

    Ferroelectrics(Gordon&Breach)   267  2002

    DOI

  • Symmetry of high-piezoelectric Pb based complex perovskites at the morphotoropic phase boundary I. Neutron diffraction study on PZN/9PT, J. Phys. Soc. Japan, 960-965(2002).

    J. Phys. Soc. Japan   71, No.3, 966-970  2002

    DOI

  • Colosal response induced bu hetero-structure fluctuation

    Y.Uesu

    Symposia of Material Research Society Japan    2002

  • SHG Microscopic studies on low temperature phase transitions of SrTiO3

    Y.Uesu

    7th RCBJ Symposium on Ferroelectricity, St.Peterburg, Russia    2002

  • Light-induced ESR of dye-doped KDP, Ferroelectrics

    Ferroelectrics   264  2001

    DOI

  • SHG interference microscope as a tool of nondestructive observation of ferroelectric 180 degrees domain structures

    Ferroelectrics   253  2001

  • Morphology and thermochromic phase transition of merocyanine J-aggregate monolayers at the air-water and solid-water interfaces

    J. Chem. Phys.   115 (3)  2001

    DOI

  • Mesoscopic Hetero-Phase Fluctuations and Related Physical Properties

    UESU Yoshiaki, YAMADA Yasusada

    X-RAYS   43 ( 1 ) 96 - 101  2001

     View Summary

    Some materials exhibit a huge response to an applied field, the phenomenon being closely related to the mesoscopic hetero-phase fluctuation in materials. It has been revealed that the phenomenon is ubiquitous and is found in variety of materials such as martensitic alloys, dielectric relaxors, colossal magneto-resistance materials and so on. The response characteristics may be termed"super-susceptibility". Examples of the phenomenon and the computer simulation using the time-dependent Ginzburg-Landau theory are reviewed.

    DOI CiNii

  • Evolution of Long-Range Order in Relaxors

    UESU Yoshiaki, FUJISHIRO Kouji, YAMADA Yasusada, YAMAMOTO Naoki

    X-RAYS   43 ( 3 ) 241 - 247  2001

     View Summary

    The colossal dielectric properties of relaxors are related to the appearance of polar nanoregions in cubic nonpolar matrix. In this hetero-phase structure, the long-range order is locally clamped and the average symmetry of the specimen remains to be cubic down to the low temperature. However, the application of the electric field yields the evolution of longrange order and the ferroelectric state prevails on the specimen. However, it develops with quite long incubation time. We report here this peculiar phenomenon which was observed by optical, X-ray and TEM techniques, and discuss the origin.

    DOI CiNii

  • Universal phase diagram for high-piezoelectric system

    Appl. Phys. Lett.   79  2001

    DOI

  • Light-induced ESR of dye-doped KDP, Ferroelectrics

    Ferroelectrics   264  2001

    DOI

  • SHG interference microscope as a tool of nondestructive observation of ferroelectric 180 degrees domain structures

    Ferroelectrics   253  2001

  • Morphology and thermochromic phase transition of merocyanine J-aggregate monolayers at the air-water and solid-water interfaces

    J. Chem. Phys.   115 (3)  2001

    DOI

  • Universal phase diagram for high-piezoelectric system

    Appl. Phys. Lett.   79  2001

    DOI

  • Temperature dependence of the generalized vibrational density of states of sodium bismuth titanate in the ferroelectric phase

    SG Lushnikova, SN Gvasaliya, IG Siny, IL Sashin, VH Schmidt, Y Uesu

    SOLID STATE COMMUNICATIONS   116 ( 1 ) 41 - 45  2000

     View Summary

    This paper describes studies of relaxer ferroelectric Na1/2Bi1/2TiO3 (NBT) by inelastic incoherent neutron scattering at temperatures from 50 to 300 K. Experimental time-of-flight spectra were recalculated into the generalized vibrational density of states (VDOS) function in terms of one-particle incoherent approximation and compared with the behavior of Raman spectra. It is shown that the VDOS of NET in the ferroelectric phase has nontrivial temperature dependence. The relation between the temperature dependence of VDOS and the instability of the NET crystalline lattice below room temperature is discussed. (C) 2000 Published by Elsevier Science Ltd.

    DOI CiNii

  • Structural phase transition of merocyanin J-aggregate induced by ion-recombination in the aqueous sub-phase

    N.Kato, K.Saito, Y.Uesu

    Chem.Phys.Lett.   326 ( 5/6 ) 395 - 399  2000

    DOI CiNii

  • Domain structure in the ferroelastic langbeinite K2Cd1.6Mn0.4(SO4)(3)

    R Vlokh, Skab, I, O Vlokh, Y Uesu, Y Yamada

    FERROELECTRICS   242 ( 1-4 ) 47 - +  2000

     View Summary

    The ferroelastic phase transition in K2Cd1.6Mn0.4(SO4)(3) Solid solution was investigated by optical microscopy method. The existence of the permissible domain structure in those compounds in whole temperature region below 23F222 second order phase transition was found. it was shown that in the crystals which belong to the isolated point, the domain walls are permissible due to enantiomorphic twinning. The determined orientation of domain walls is {110}. The investigation of the topography of the optical activity shows the change of optical rotary power in some regions in 23 phase of K2Cd0.4Mn1.6(SO4)(3) crystals. Obtained results are discussed on the base of thermodynamic potential and prototype phase with point group symmetry (4) over bar 3m.

  • Novel thermochromism of merocyanine J-aggregate monolayers

    N.Kato, T.Serata, K.Saito, Y.Uesu

    Mol.Cryst.Liq.Cryst.   349   199 - 202  2000

    DOI CiNii

  • SHG microscopy and SHG images of merocyanine J-aggregate monolayer at the air-water interface

    K.Saito, N.Kato, Y.Uesu

    Mol.Cryst.Liq.Cryst.   349   103 - 106  2000

    DOI CiNii

  • リラクサーにおけるヘテロ構造ゆらぎ

    上江洲由晃

    日本物理学会春の分科会,誘電体分科会   学会講演集  2000

  • リラクサーの謎ー不均一構造がもたらす巨大な圧電・誘電応答ー

    上江洲由晃

    パリティー(丸善)   20 ( 5 ) 18 - 24  2000

  • Temperature dependence of the generalized vibrational density of states of sodium bismuth titanate in the ferroelectric phase

    SG Lushnikova, SN Gvasaliya, IG Siny, IL Sashin, VH Schmidt, Y Uesu

    SOLID STATE COMMUNICATIONS   116 ( 1 ) 41 - 45  2000

     View Summary

    This paper describes studies of relaxer ferroelectric Na1/2Bi1/2TiO3 (NBT) by inelastic incoherent neutron scattering at temperatures from 50 to 300 K. Experimental time-of-flight spectra were recalculated into the generalized vibrational density of states (VDOS) function in terms of one-particle incoherent approximation and compared with the behavior of Raman spectra. It is shown that the VDOS of NET in the ferroelectric phase has nontrivial temperature dependence. The relation between the temperature dependence of VDOS and the instability of the NET crystalline lattice below room temperature is discussed. (C) 2000 Published by Elsevier Science Ltd.

    DOI CiNii

  • Structural phase transition of merocyanin J-aggregate induced by ion-recombination in the aqueous sub-phase

    N.Kato, K.Saito, Y.Uesu

    Chem.Phys.Lett.   326 ( 5/6 ) 395 - 399  2000

    DOI CiNii

  • Domain structure in the ferroelastic langbeinite K2Cd1.6Mn0.4(SO4)(3)

    R Vlokh, Skab, I, O Vlokh, Y Uesu, Y Yamada

    FERROELECTRICS   242 ( 1-4 ) 47 - +  2000

     View Summary

    The ferroelastic phase transition in K2Cd1.6Mn0.4(SO4)(3) Solid solution was investigated by optical microscopy method. The existence of the permissible domain structure in those compounds in whole temperature region below 23F222 second order phase transition was found. it was shown that in the crystals which belong to the isolated point, the domain walls are permissible due to enantiomorphic twinning. The determined orientation of domain walls is {110}. The investigation of the topography of the optical activity shows the change of optical rotary power in some regions in 23 phase of K2Cd0.4Mn1.6(SO4)(3) crystals. Obtained results are discussed on the base of thermodynamic potential and prototype phase with point group symmetry (4) over bar 3m.

  • Novel thermochromism of merocyanine J-aggregate monolayers

    N.Kato, T.Serata, K.Saito, Y.Uesu

    Mol.Cryst.Liq.Cryst.   349   199 - 202  2000

    DOI CiNii

  • SHG microscopy and SHG images of merocyanine J-aggregate monolayer at the air-water interface

    K.Saito, N.Kato, Y.Uesu

    Mol.Cryst.Liq.Cryst.   349   103 - 106  2000

    DOI CiNii

  • Optical second harmonic images of Merocyanine J-aggregate monolayers at air-water surface

    Thin Solid Films/Elsevier   338(5-8)  1999

    DOI

  • Observation of merocyanine J-aggregate domains in mixed monolayers using SHG/fluorescence and atomic force microscopes

    Chemical Physics Letters, Elsvier   312,pp.115-120  1999

    DOI

  • Optical second harmonic generation of merocyanine J-agregate monolayers at the air-water interface

    Thin Solid Films, Elsevier   338,pp.5-8  1999

    DOI

  • Reduction of the specular reflectivity from Feinberg's Cat conjugator operating in auto-oscillation mode

    Applied Physics B, Springer-Verlag   68,pp.953-957  1999

    DOI

  • Multi-purpose nonlinear optical microscope. Its principle and applications to polar thin-film observation

    Physics of the Solid State, American Institute of Physics   41,no.5,pp.688-692  1999

    DOI

  • 非線形顕微法

    上江洲由晃, 栗村直, 加藤徳剛

    特許番号 特願平 11-121083号    1999

  • Optical second harmonic images of Merocyanine J-aggregate monolayers at air-water surface

    Thin Solid Films/Elsevier   338(5-8)  1999

    DOI

  • Observation of merocyanine J-aggregate domains in mixed monolayers using SHG/fluorescence and atomic force microscopes

    Chemical Physics Letters, Elsvier   312,pp.115-120  1999

    DOI

  • Optical second harmonic generation of merocyanine J-agregate monolayers at the air-water interface

    Thin Solid Films, Elsevier   338,pp.5-8  1999

    DOI

  • Reduction of the specular reflectivity from Feinberg's Cat conjugator operating in auto-oscillation mode

    Applied Physics B, Springer-Verlag   68,pp.953-957  1999

    DOI

  • Multi-purpose nonlinear optical microscope. Its principle and applications to polar thin-film observation

    Y. Uesu, N. Kato

    Physics of the Solid State   41 ( 5 ) 688 - 692  1999

     View Summary

    Multi-purpose nonlinear optical microscope is an optical microscope which images 2D distribution of the optical second harmonic (SH) waves from a specimen. Image contrast can be obtained either by inhomogeneous distribution of nonlinear optical tensor components or by the interference between SH waves from a specimen and a standard plate. This microscope also functions as a fluorescence (FL) microscope, and SH and FL images can be obtained from the same part of a specimen. Absorption and FL spectra from a specific part of a specimen are measured through an optical fiber which connects an ocular with a polychromator. These functions are especially useful for investigation of the J-aggregate state of polar dye molecules. Several photographs taken by the microscope revealed the structure of merocyanine dye/arachidic acid mixed monolayer and the role of bridge ions in the subphase. © 1999 American Institute of Physics.

    DOI

  • Hexagon formation in photorefractive crystals as mirrorless coherent oscillation

    J.Opt.Soc.Amer./米国光学会   B15,(2065-2069)  1998

  • Structural and Optical Studies of Development of the Long-range Order in Ferroelectric Relaxor PZN/9%PT

    Ferroelectrics/Gordon & Breach   217,(319-325)  1998

  • Optical and nonlinear optical studies of relaxor PMN

    J.Korean Phys.Soc.   32,(S964-S966)  1998

  • Optical observation of heterophase and domain structures in relaxor ferroelectric PMN/PT

    Jpn.J.Appl.Phys./応用物理学会欧文誌刊行会   37, (5246-5248)  1998

    DOI

  • リラクサーの構造と物性

    固体物理   336;6(498-509)  1998

  • Simulation study of zigzag domain boundary formation in ferroelectric-ferroelastics using the TDGL equation

    Ferroelectrics/Gordon & Breach   219,(215-224)  1998

  • Appearence of paraelactric phase as ferroelastic domain walls in K2Cd2(SO4)3 single crystals

    J.Phys.Soc.Jpn. /日本物理学会   67, (3335-3337)  1998

    DOI

  • AFM studies of Self-Pattern Formation in Mixed Monolayer of Polar and Nonpolar Organic Molecules

    J.Korean Phys.Soc.   32,S1076-S1078  1998

  • SHG Microscope: Principle and its Application

    J.Korean Phys.Soc.   32,S461  1998

  • Self-ordering of polar merocyanine dye molecules in Langmuir-Blodgett films

    Ferroelectrics/ Gordon & Breach   218,(257-265)  1998

  • HERMESを用いたリラクサーの構造変化

    東北大学金属材料研究所ワークショップ「中性子回折による化合物磁性体の構造の研究」   1998.12.14  1998

  • リラクサーの構造変化と誘電特性

    日本結晶学会シンポジウム「物性科学と結晶学」   1998.11.21  1998

  • AFM and SHGM studies of merocyanine J-aggregate monolayers

    1st International Symposium on Atomic Scale Processing and Novel Properties in Nanoscopic Meterials (Osaka Univ.)   1998.11.10  1998

  • Multi-purpose nonlinear optical microscope -Principle and its applications to polar thin films- (ロシア科学アカデミー、ヨッフェ物理工学研究所創立80周年記念シンポジウム、「21世紀の転回点における物理学」)

    ロシア科学アカデミー,Phys.Solid State   1998.9.28 41,5(1999)(688-692)  1998

  • Observation of Ferroic Domains by Means of the Optical Second Harmonic Generation

    UESU Yoshiaki

    X-RAYS   40;5(335-340) ( 5 ) 335 - 340  1998

     View Summary

    The optical second harmonic generation can be applied to the observation of ferroic domains. In particular, ferroelectric 180° domain structures were successfully observed using a nonlinear microscope termed SHG microscope. The principle utilizes the phase difference of the second harmonic waves produced in domains with opposite polarizations and the interference effect was utilized to make the intensity contrast. Other applications to the J-aagre-gate in monomolecular films and antiferromagnetic domain structure are also possible using the SHG microscope.

    DOI CiNii

  • Hexagon formation in photorefractive crystals as mirrorless coherent oscillation

    J.Opt.Soc.Amer./米国光学会   B15,(2065-2069)  1998

  • Structural and Optical Studies of Development of the Long-range Order in Ferroelectric Relaxor PZN/9%PT

    Ferroelectrics/Gordon & Breach   217,(319-325)  1998

  • Optical and nonlinear optical studies of relaxor PMN

    J.Korean Phys.Soc.   32,(S964-S966)  1998

  • Optical observation of heterophase and domain structures in relaxor ferroelectric PMN/PT

    Jpn.J.Appl.Phys./応用物理学会欧文誌刊行会   37, (5246-5248)  1998

    DOI

  • Simulation study of zigzag domain boundary formation in ferroelectric-ferroelastics using the TDGL equation

    Ferroelectrics/Gordon & Breach   219,(215-224)  1998

  • Appearence of paraelactric phase as ferroelastic domain walls in K2Cd2(SO4)3 single crystals

    J.Phys.Soc.Jpn. /日本物理学会   67, (3335-3337)  1998

    DOI

  • AFM studies of Self-Pattern Formation in Mixed Monolayer of Polar and Nonpolar Organic Molecules

    J.Korean Phys.Soc.   32,S1076-S1078  1998

  • SHG Microscope: Principle and its Application

    J.Korean Phys.Soc.   32,S461  1998

  • Self-ordering of polar merocyanine dye molecules in Langmuir-Blodgett films

    Ferroelectrics/ Gordon & Breach   218,(257-265)  1998

  • AFM and SHGM studies of merocyanine J-aggregate monolayers

    1st International Symposium on Atomic Scale Processing and Novel Properties in Nanoscopic Meterials (Osaka Univ.)   1998.11.10  1998

  • Multi-purpose nonlinear optical microscope -Principle and its applications to polar thin films- (ロシア科学アカデミー、ヨッフェ物理工学研究所創立80周年記念シンポジウム、「21世紀の転回点における物理学」)

    ロシア科学アカデミー,Phys.Solid State   1998.9.28 41,5(1999)(688-692)  1998

  • 電磁気学

    産業図書(株)    1997

  • Non-destructive observation of ferroelectric 180 domains by SHG microscope

    Ferroelectrics   191  1997

  • Two-dimensional observation of the Maker fringe and its application to the poling state evaluation of ferrolelectric domains

    Appl.Optics   36  1997

  • Application of the second harmonic generation microscope to nondestructive observation of periodically-poled ferroelectric domians in quasi-phase-matched wavelength converters:

    J.Appl.Phys.   81;1  1997

    DOI

  • 非線形光学顕微鏡の開発と周期性反転分域の非破壊観察

    科学新聞   4月18日号  1997

  • 非線形光学顕微鏡の開発と周期性反転分域の非破壊観察

    電波新聞   4月10日号  1997

  • 非線形光学顕微鏡の開発と周期性反転分域の非破壊観察

    日本工業新聞   3月28日号  1997

  • 非線形光学顕微鏡の開発と周期性反転分域の非破壊観察

    日刊工業新聞   3月28日号  1997

  • 波長変換素子を非破壊評価―SHG顕微鏡を利用、分域構造観察手法を開発―

    科学新聞   4月16日号  1997

  • 波長変換素子の180度分域構造―早大が非破壊観察に成功―

    電波新聞   4月10日号  1997

  • 波長変換素子の構造、破壊しないで観察―早稲田大学が顕微鏡を開発―

    日刊工業新聞   3月28日号  1997

  • 非破壊観察方を開発―早大強誘電体の分域構造―

    日刊工業新聞   3月28日号  1997

  • Microstructure related to a low-temperature transition in Ba2NaNb5O15

    Ferroelectrics   190,13-18.  1997

  • 分極反転光デバイスの光第2高調波による非破壊評価

    光学(日本光学会)   26,437  1997

  • Non-destructive observations of 180 degree ferroelectric domain using the nonlinear optical (SHG) microscope

    Ferroelectrics   191, 135-140  1997

  • Application of the second harmonic generation microscope to nondestructive observation of periodically-poled ferroelectric domians in quasi-phase matched wavelength converters

    J.Appl.Phys.   81, 369-375  1997

    DOI

  • Two-dimensional observation of the Maker fringe and its application to the poling state evaluation of ferroelectric domains,

    Appl. Optics   36,602-605  1997

  • Non-destructive observation of ferroelectric 180 domains by SHG microscope

    Ferroelectrics   191  1997

  • Two-dimensional observation of the Maker fringe and its application to the poling state evaluation of ferrolelectric domains

    Appl.Optics   36  1997

  • Application of the second harmonic generation microscope to nondestructive observation of periodically-poled ferroelectric domians in quasi-phase-matched wavelength converters:

    J.Appl.Phys.   81;1  1997

    DOI

  • Microstructure related to a low-temperature transition in Ba2NaNb5O15

    Ferroelectrics   190,13-18.  1997

  • Non-destructive observations of 180 degree ferroelectric domain using the nonlinear optical (SHG) microscope

    Ferroelectrics   191, 135-140  1997

  • Application of the second harmonic generation microscope to nondestructive observation of periodically-poled ferroelectric domians in quasi-phase matched wavelength converters

    J.Appl.Phys.   81, 369-375  1997

    DOI

  • Two-dimensional observation of the Maker fringe and its application to the poling state evaluation of ferroelectric domains,

    Appl. Optics   36,602-605  1997

  • Neutron scattering and nonlinear optical studies on the phase transition of ferroelectric relaxor PMN

    J.Korean Phys   Soc.,29  1996

  • Nonlinear optical study of phase transition in lead magnesium niobate

    Jpn.J.Appl.Phys.   35  1996

    DOI

  • Domain inversion by an electron-beam induced electric field in Mg:LiNb03 and LiTa03

    Jpn.J.Appl.Phys.   35  1996

    DOI

  • Total reflection-type SHG microscope

    Ferroelectrics   184  1996

  • Optical and x-ray Studies on the low-temperature phase transition of Ba2NaNb5015

    J.Phys.:Condens.Matter   8  1996

    DOI

  • Domain inversion in ferroelectric MgO:LiNb03 by applying electric fields

    Appl.Phys.Lett.   69  1996

    DOI

  • Neutron scattering and nonlinear optical studies on the phase transition of ferroelectric relaxor PMN

    J.Korean Phys   Soc.,29  1996

  • Nonlinear optical study of phase transition in lead magnesium niobate

    Jpn.J.Appl.Phys.   35  1996

    DOI

  • Domain inversion by an electron-beam induced electric field in Mg:LiNb03 and LiTa03

    Jpn.J.Appl.Phys.   35  1996

    DOI

  • Total reflection-type SHG microscope

    Ferroelectrics   184  1996

  • Optical and x-ray Studies on the low-temperature phase transition of Ba2NaNb5015

    J.Phys.:Condens.Matter   8  1996

    DOI

  • Domain inversion in ferroelectric MgO:LiNb03 by applying electric fields

    Appl.Phys.Lett.   69  1996

    DOI

  • 位相共役顕微鏡

    先端オプティクス用光新機能素子技術に関する調査研究報告書/日本機械工業連合会,日本オプトメカトロニクス協会    1995

  • 特集「脚光を浴びるフォトリフラクティブ効果とその応用」,ノベルティーフィルターを用いた動体検出

    OPTRONICS/オプトロニクス社   169;5  1995

  • Memory effect, defect density wave, and related microdomain structure in an incommensurate phase of barium sodium niobate

    S. Mori, N. Yamamoto, Y. Koyama, Y. Uesu

    Physical Review B   51 ( 1 ) 73 - 76  1995

     View Summary

    A microstructure causing the memory effect in the incommensurate phase of barium sodium niobate was investigated by means of a transmission electron microscope. A type of microdomain structure, which is constituted of a complicated array of microscopic ferroelastic domains with a modulation along the [100] direction, is found. Because this microdomain structure appears reversibly during the heating and cooling processes, the microdomain structure is directly related to the memory effect. © 1995 The American Physical Society.

    DOI

  • Evolution of a ferrolectric domain structure in an incommensurate pahse of barium sodium niobate

    Physical Review B/American Institute of Physics   52  1995

  • Memory effect in an incommensurate phase of barium sodium niobate

    Ferroelectrics/Gordon & Breach   169  1995

  • Nonlinear optical properties of new ferroelectric LaBGeO5

    Ferroelectrics/Gordon & Breach   169  1995

  • Simulational and experimental studies on anomalous reflectivity of phase conjugate wave

    Ferroelectrics/Gordon & Breach   170  1995

  • Recent development of optical novelty filter and dynamics of optical noveltry filter with use of the CAT-type self-pumped phase conjugate mirror

    Ferroelectrics/Gordon & Breach   172  1995

    DOI

  • New nonlinear optical microscope and its application to the observation of ferroelectric domain structure

    Ferroelectrics/Gordon & Breach   170  1995

  • Optical second harmonic images of 90o domain structure in BaTiO3 and periodically inverted antiparallel domains in LiTaO3

    Applied Physics Letters/American Institute of Physics   66  1995

    DOI

  • Memory effect, defect density wave, andrelated microdomain structure in an incommensurate phase of barium sodium niobate

    Physical Review B/American Institute of Physics   51  1995

    DOI

  • Evolution of a ferrolectric domain structure in an incommensurate pahse of barium sodium niobate

    Physical Review B/American Institute of Physics   52  1995

  • Memory effect in an incommensurate phase of barium sodium niobate

    Ferroelectrics/Gordon & Breach   169  1995

  • Nonlinear optical properties of new ferroelectric LaBGeO5

    Ferroelectrics/Gordon & Breach   169  1995

  • Simulational and experimental studies on anomalous reflectivity of phase conjugate wave

    Ferroelectrics/Gordon & Breach   170  1995

  • Recent development of optical novelty filter and dynamics of optical noveltry filter with use of the CAT-type self-pumped phase conjugate mirror

    Ferroelectrics/Gordon & Breach   172  1995

    DOI

  • New nonlinear optical microscope and its application to the observation of ferroelectric domain structure

    Ferroelectrics/Gordon & Breach   170  1995

  • Optical second harmonic images of 90o domain structure in BaTiO3 and periodically inverted antiparallel domains in LiTaO3

    Applied Physics Letters/American Institute of Physics   66  1995

    DOI

  • Method of measuring the time for forming refractive index grating of a photo-nonlinear medium

    米国特許   Patent number 5,303,032  1994

  • Method of measuring the time for forming refractive index grating of a photo-nonlinear medium

    米国特許   Patent number 5,303,032  1994

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Industrial Property Rights

  • 非線形顕微方法

    Patent

     View Summary

    特開2000-310799

 

Overseas Activities

  • 巨大物性をもたらすヘテロ構造材料の創製およびヘテロ構造のSHG干渉顕微鏡観察

    2009.03
    -
    2009.10

    イギリス   オックスフォード大学

Internal Special Research Projects

  • ニオブ酸リチウム・タンタル酸リチウム混晶系の非線形光学特性に関する国際共同研究

    2011  

     View Summary

    I. 研究成果ニオブ酸リチウム(LN)およびタンタル酸リチウム(LT)は、能動光学素子、波長変換素子、表面波フィルター、焦電素子として広く使用されている強誘電体であり、数多くの研究がなされてきた。それにもかかわらず、未だ解明されていない本質的な問題が存在する。このような問題点は日英でほとんど同時に認識され独立に研究が始められた。本研究は認識を共有する日英の研究機関が研究チームを組織し、密接な連携のもとにそれぞれの研究所がもつユニークな装置を用いてこの未解決の問題に総合的に取り組み、以下のような成果をあげた。(1)パルスレーザー成膜法(PLD)を用いて、LNおよびLT単結晶をターゲットにしたLN/LT超格子薄膜をサファイア(0001)単結晶基板の上に作成することに、世界で初めて成功した。(2)この膜のX線回折装置(XRD)および電子顕微鏡(TEM)観察から、デザインした周期をもつエピタキシャル超格子膜となっていることを確認した。(3)組成をTEMに付属したエネルギー分散X線スペクトロメータを用いて解析した。その結果、LN層とLT層は単一組成ではなく互いに混合していることを明らかにした。(4)XRD解析から決定した格子定数の値から、薄膜の対称性はバルクとは異なりLiが欠損している相であることを明らかにした。(5)バルクではこのLi欠損層は対称性が中心対称性をもつ単斜晶であるが、LN/LT超格子膜の場合には対称中心のない極性をもつ単斜晶であることを明らかにした。II. 国際ミニシンポジウムの開催これらの成果を議論するために、Oxford大学のMike Glazer教授をこのプログラムで早稲田大学に招聘し、下記のようなミニシンポジウムを開催した。参加者は早稲田大学の学部学生、大学院学生、他大学の教員などを含めて40名近くになり、活発な議論を行った。LNミニセミナー 「LiNbO3関連物質の基礎と応用の最先端」Mini-seminar on “Frontiers of fundamental and applications of LiNbO3 and related materials”開催場所:早稲田大学先進理工学部物理学科&応用物理学科会議室(55号館N棟2階)開催日時:11月2日(水)午後1時~4時講演者&講演タイトル1. 13:00-14:00:Mike Glazer (Oxford大学物理学科教授)“On changing the birefringence of LiTaO3”2. 14:00-15:00: Kenji Kitamura (北村健二)(物質材料機構、フェロー)"Pyroelectric and Photogalvanic Surface Potential of Ferroelectric Crystals"「強誘電体結晶における焦電・光起電力表面電荷」3. 15:00-15:30: Yasunori Furukawa (古川保典)(オキサイド(株)社長)  “Introduction of spinoff venture company from NIMS and development of over100 mW CW 355 nm laser with PPMgSLT”4. 15:30-16:00: Sunao Kurimura(栗村直)(物質材料機構、主幹研究員)   “Nonlinear optical devices based on Lithium Niobate family”

  • SHG干渉顕微鏡を用いたマルチフェロ物質のドメイン3次元観察

    2009  

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    強誘電性、強弾性と磁気秩序が共存するマルチフェロ物質に着目し、そのメソスコピックスケールの分域構造を、光第2高調波発生(SHG)干渉顕微鏡を用いて3次元非破壊観察することを目的とする。それにより異なる秩序状態の相互作用や外場のもとでの応答を実空間で視覚化することにより、マルチフェロの起因を解明する。最終目標のひとつとして、SHG干渉顕微鏡を医学におけるMRIやCT診断器と同じ、材料の新しい診断装置に発展させたいと考えている。誰でも使用でき、汎用性豊かな日本発信の新しい顕微鏡を完成させ、それを用いてマルチフェロの発現機構に迫る。 このような趣旨のもとで試料が発生する光第2高調波(SHG)をプローブとする新しい非線形光学顕微鏡(SHG干渉顕微鏡)を開発してきた。この顕微鏡の特色は、(1)従来の光学顕微鏡では観察できない試料内のヘテロ構造、たとえば強誘電体の180°分域構造、を観察できること、(2)非破壊で3次元観察が可能であること、(3)SHGが空間反転対称性の破れと時間反転対称性の破れに敏感な物理現象であることを利用して、強誘電ドメインと磁気ドメインを識別して観察できること、(4)無機物質だけでなく生体物質の極性構造を観察できること、などである。 この特色を生かして2009年度は以下の成果を得た(1)典型的なマルチフェロBiFeO3単結晶の独立なSHGテンソルの大きさと符号を決定し、また磁気ドメインと強誘電ドメインを識別できるSHGテンソル成分を明らかにしたこと(Appl. Phys. Lett. 95, 082904 (2009))。(2)180度分域構造を識別するためにわれわれは干渉法、すなわち試料が発生する第2高調波と、一様な参照波を干渉させることにより、分域構造を明暗の強度として識別している。一方で干渉なしでも分域構造は見えるとする論文がいくつか報告されている。そこでわれわれはこの問題を強く絞った基本波を用いた光学系という実際に使用している光学系の上に立って、非線形波動方程式を数値解析した。これによると干渉させない場合は、分域そのものではなく分域境界が黒くみえることを証明した。また疑似位相整合素子に使用されている周期性反転分極の空間分解能が、その周期にも依存することを明らかにした。(3)筋繊維のSHG干渉顕微鏡観察で石渡研究室との共同研究を進めた。現在論文準備中であるが応用物理学会シンポジウム、および物理学会シンポジウムで成果を講演した。

  • 酸化物超格子薄膜を用いたナノメタ物質の創製と構造・物性評価

    2008  

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    本研究は、新しいメタマテリアルすなわち1+1が2以上になる物質を探索しようというもので、この目的のために、リラクサーと呼ばれている複合酸化物と強誘電体酸化物との超格子薄膜を単位格子の精度、0.4 nmで制御して作成し、その構造と誘電特性を評価し、超格子特有の特異な現象を見つけたものである。 このような人工超格子の研究はEsakiの半導体超格子の研究が有名であり、これは異なった種類の原子を結晶基板の上に原子スケールで交互に堆積させ、バンド構造を制御して自然界では得られない特異な電子状態を作り出すという考えである。私たちはこの人工超格子を酸化物、特にぺロブスカイト構造をもつ誘電薄膜を用いて新しい機能を作り出せないかを目的とした研究にチャレンジしてきた。これは、半導体や磁性体と異なって強誘電体の機能は構造と直接結びついているからで、そのために薄膜、多層膜、超格子は誘電体分野で非常に魅力的な方法となっている。  成果は次のように要約される。(1)組成比の異なる強誘電体/リラクサー超格子膜PSN/PTをPLD法により作成し、超格子周期の乱れが無く、層間に介在するインターフェイスの影響が非常に少ない薄膜の作成法を確立した。(2)作成した超格子膜のメソスコピックな構造をX線回折法により解析し、超格子中のPSNとPTの格子定数をPT組成比の関数として決定した。PSNの格子定数は組成比にほとんど依存しないのに対し、PTの格子定数はある組成比の時大きく増加することを発見した。これはPTの配向性の変化、すなわち自発分極が面内にあるa分域状態から面に垂直方向なc分域に変わることを示している。 (3)同じ膜について誘電応答特性を測定し、PTの格子定数が変化する組成比で超格子固有の誘電率が増大する現象を見出した。この誘電特性の挙動と構造変化を説明する可能なモデルを検討した。これらの結果は、単位格子スケールで制御した強誘電体/リラクサー超格子膜の作成法を確立したこと、作成した超格子がインターフェイスの影響のない良質な膜であること、また超格子がバルク結晶や単層膜とは異なる物性を示すことを明確に示した点で、今後の誘電体薄膜物理に重要な指針を与える研究である。 結果の主なものは、Appl.Phys.Lett.およびJ.Appl.Phys.に掲載されている。

  • 筋繊維が示す反転分極構造の観察と擬似位相整合素子の可能性

    2008  

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    SHGは空間反転対称性の破れと時間反転対称性の破れを感度良く検出できる実験手段である。申請者は早くからSHGが強誘電体の自発分極に非常に敏感な量であり、大きなダイナミックレンジで強誘電体の秩序変数である自発分極の変化を検出でき、また臨界指数を決定する感度の高い測定であることを指摘した(例えばJ.J.Appl.Phys.28,453(1989), J.Phys.Soc.Jpn. 60,2461(1991))。またFiebigらの観察に先立って強誘電分域の2次元観察をSHG顕微鏡で行った(Appl.Phys.Lett.66,2165(1995))。さらに従来不可能とされてきた強誘電体の180°分域構造を、SHGの干渉を用いれば観測可能であることを指摘し、疑似位相整合素子(QPM)の周期性反転分極構造(PPD)の2次元観察に成功した(J.Appl.Phys.81,369(1997))。このSHG顕微鏡を用いて水面上の極性色素分子の単分子膜の会合状態を観測した(J.Chem.Phys.115,1473 (2001))。また反転分域の3次元観察を可能にする4位相干渉法を開発して、LiNbO3の電場のもとでのドメイン反転を観察した(Ferroelectrics 304,99(2004))。 本研究では、ドメインのより一般的な3次元観察を可能にするため、SHG干渉顕微鏡法に共焦点光学系を導入し、LiTaO3-QPM素子に書き込まれた周期8μmのPPDのSHG断層写真をとることに成功した。この一連の研究で、ある強誘電結晶では試料内部のドメイン構造が明確に観察されるのに対し、他の強誘電結晶あるいは同じ結晶でも異なるSHGテンソル成分を用いると内部からのSH強度が非常に微弱になり、ドメイン境界のみが強調して観測されることが明らかになってきた。この原因について、極最近、強くレーザービームを絞った場合に起こる共焦点系に特有の問題であることを突き止め、3D可視化の一般的な条件を求めた。このようなSHG干渉顕微鏡を用いた非破壊3次元観察は、まだ世界のどこでもなされていないユニークな顕微法である。 ウサギの骨格筋から抽出した筋繊維のSHG観察を行った。筋繊維は半径約1mの筋原繊維の束であり、さらに筋原繊維は、ミオシンフィラメントとアクチンフィラメントからなる基本構造(サルコメア)が軸方向に約2mの周期で並んだものである。興味深いことはサルコメアを構成するミオシンロッドが逆向きの2重らせん構造を持っていることある。この構造はサルコメアが反転極構造を形成していることを予想させる。この観察はわれわれのSHG干渉顕微鏡で初めて可能になるが、実際に観察したところ確かにMバンドを中心に分極反転構造が形成されていることを明らかにした。さらに軸方向レーザーを入射させたときに予想されるSHG強度の増幅が観察された。 これらの成果を応用物理学会のシンポジウム(2007年3月)、および物理学会のシンポジウム(2008年3月)で発表し、またリトアニアのヴィリニウスで開催された第9回RCBJ強誘電体会議では「SHG tomography as a tool of material diagnosis」と題する45分の冒頭基調講演(2008年6月)を行った。 

  • 筋原線維の示すスパイラル反強誘電構造の光第2高調波干渉顕微鏡観察

    2007   石渡 信一, 島本 勇太

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    生物の筋肉は階層構造をもつ。筋肉は直径100μmの筋繊維の束からなり、この筋繊維は直径1μmの筋原線維が集合したものである。さらに1本の筋原線維は、サルコメアと呼ばれている単位が線維軸方向に約2μmの周期で規則正しく並んでいる。サルコメアはミオシンフィラメント、アクチンフィラメント、タイタン、などから構成され、極性をもつバンドと極性を持たない部位からなっている。この構造はすでに米国や日本のグループによって光第2高調波(SHG)顕微鏡で観察されている。興味深いことはサルコメアはその構造から、M線と呼ばれる中央線を挟んで極性が反対向きの構造をとるといわれている。しかしながら今まで実験で直接にこの極性構造を観察して例はなかった。本研究は、上江洲研究室で10年に渡り開発してきたSHG干渉顕微鏡を用いて、世界に先駆けてこの反転分極構造を観測した。成果をまとめると次のようになる。(1)筋繊維は期待していた以上の大きなSHGがある。強度を単純に比較すると、よく用いられる非線形光学結晶ニオブ酸リチウムのd22成分の1/700に達する。(2)周期反転分極をもつということは、筋原線維を一種の反強誘電体とみなすことができる。(3)筋原線維の周期性反転分極構造は、位相を同じにして束ねられて筋繊維となる。SHG強度が大きい理由もこのコヒーレントな構造に由来する。(4)もし軸方向に光を通すと、筋繊維は一種の擬似位相素子となる。周期性が2μmであることから、紫外光への波長変換素子として魅力がある。生体の中でこの現象を利用すれば、拒否反応なく埋め込んだ波長可変の光源ともなるであろう。

  • 量子常誘電体の不純物効果ー本質的不均一性がもたらす巨大応答ー

    2007   上江洲 由晃, 浅沼 周太郎

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    凝縮系物理においては、外場に対して大きな応答特性をもつ物質を開発することが基礎の観点からも応用の観点からももっとも重要なテーマのひとつとなっている。線形応答理論によれば、原子分子のミクロな揺らぎが大きな感受率をもたらす。このもっとも典型的な現象が相転移である。そこでは相転移と直接関連した秩序変数のゆらぎが発散的に増大し、秩序変数と共役な外場に対する感受率が巨大な値をとる。この現象は2つの競合する力が働き、その拮抗する温度で系が不安定になるために生じる。強誘電体の場合には、強誘電相を引き起こす長距離クーロン力と、常誘電相に引き戻そうとする短距離的な復元力がその役割をはたす。この考えを推し進めて、より多くの力が競合する状況を作り出せば種々の外場に対して物質は不安定性を示すことになり、多機能性をもった系や巨大な応答特性をもつ材料を開発することが可能となるであろう。 本研究はこのような観点から研究を進め、典型的な量子常誘電体であるペロブスカイト酸化物タンタル酸カリウム(KTaO3、KTO)にリチウム(Li)をわずかに添加した系(KLT)を対象としている。 実験手段として、SHG顕微鏡、X線回折、中性子散乱、誘電スペクトロメータを相補的に用いて、従来知られていなかった、あるいは非常に曖昧な概念しか存在しなかったKLTの極性状態の秩序形成と臨界現象に関して次のような結論を得た。(1) KLTがリラクサーであることを4つの基準を設定し、それをすべて満たしていることを実験的に明らかにした。(2) KLTの複雑な極性状態の変化を、Li濃度、温度、電場の多元パラメター空間で初めて明らかにした。(3) KLTの臨界最終点が三重臨界点の近くにあり、そのために大きな誘電特性がもたらされることを明らかにした。これらの結果を研究業績欄に示す5つの論文((1)~(5))に発表した。

  • 自然の不均一構造を模倣する薄膜の作成とその物性

    2005   福永 守, 浅沼 周太郎

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    高温でのSrTiO3の複素誘電率を詳しく測定し、この結果がCaCu4Ti3O12と非常に類似していること、またMaxwell-Wagner型の不均一2相モデルで定量的に説明できることを示した。巨大な誘電率は見かけのもので、厚い相の電気伝導率がアレニウス型の温度依存性をすることによりもたらされる。(JJAP, 44,No.9B,2005).リラクサーPb(Sc1/2Nb1/2)O3(PSN)薄膜、およびPSNと強誘電体PbTiO3(PT)のモルフォトロピック相境界(MPB)組成薄膜をパルスレーザー成膜(PLD)法で作成し、その構造の評価を行った。その結果、室温ではPSNは擬立方晶、MPB組成をもつPSN/PTは単斜晶であることを明らかにした。これは薄膜についての初めての報告である。(Jpn.J.Appl.Phys.:45, No.1,L42-L45, 2006)温度に対してフラットで巨大な誘電率をもつが誘電損の大きなCaCu3Ti4O12(CCTO)をCaTiO3で挟んだ薄膜を作成し、誘電損を格段に減少させることに成功した。(2006年度春の物理学会誘電体分科会発表予定)Liを添加した量子常誘電体KTaO3の構造相転移をSHG顕微鏡、X線回折、中性子散乱、誘電測定を駆使して測定し、電場のもとで著しい経歴依存性を示すこと、低温では秩序変数は非エルゴード的な挙動示すこと、極性ナノ領域の発生に対応する中間相があることを見出した。これらの事実はこの系がリラクサーであることを示している。(Phys.Rev.B72, 144103(2005))

  • リラクサーの物理 -ナノクラスター形成がもたらす巨大応答特性-

    2004  

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    パルスレーザーデポジション成膜(PLD)装置を用いて、次に示すペロブスカイト複合酸化物薄膜の作成を行い。またその構造と物性を評価した。(1)モルフォトロピック相境界組成をもつリラクサーPb(Sc1/2Nb1/2)O3(PSN)と強誘電体PbTiO3(PT)との混晶系PSN/43%PTのセラミックスおよび薄膜を作成した。まずバルク結晶について、その相図を詳細に決定した。とくにMPBの構造は、Tiの組成比に依存して、非常に複雑な様相―ある場合にはナノスケールのchemically disordered状態―を示すことを見出した。一方、薄膜の場合には、MPBでは単斜晶Pmとなること、しかし基板と薄膜の厚さに依存して、複雑な分域が観測された。また高温では非極性正方晶となることを見出し、バルク結晶とは異なり、950Kまで立方晶にはならなかった。(2)量子常誘電体SrTiO3のエピタキシャル薄膜を厚さを変えて作成した。この結果、室温ではバルク結晶と殆ど変わらない誘電率は、低温とともに増加したが、10K付近でゆるやかな極大をとったあと減少した、厚さを増すと誘電率の大きさは増加し、ピーク温度は高温側にシフトした。またいずれの場合も著しい周波数分散が観測された。現在、Ginzburg-Landau理論で解析を行っている。(3)巨大誘電緩和特性を示すCaCu3Ti4O12(CCTO)とCaTiO3からなる多層膜の作成および電荷整列ペロブスカイト型マンガン酸化物薄膜Pr0.7Ca0.3MnO3(PCMO)膜をエピタキシャルに成長させた。特にPCMOにパルス電場をかけると、光学反射率が同様に不揮発かつ可逆的に変化する現象を発見した。これは新しいタイプの光スイッチ、光メモリーとなりうるものである。

  • 反転分域構造その場観察用光第2高調波干渉顕微鏡の実用化

    2001  

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    本研究室では光第2高調波(SH波)を用いた非線形光学干渉顕微鏡を開発し、それを用いて従来観測不可能とされてきた180度強誘電分域構造を非破壊で観測することに成功した。本研究は、この方法をさらに改良し、深さ方向の分域構造をも観察できるようにした。すなわち180度強誘電分域の3次元観察を初めて可能にしたものである。 原理は試料が発生するSH波と、標準結晶板が発生するSH波を干渉させ、分域構造に対応したコントラストを生じさせるというものである。3次元観察のためには、従来やってきたような2つのSH波の位相が0だけでは知見は得られない。この他に、90度、-90度、および180度の4つの位相を用いて、干渉像を撮影し、それからh関数と名付ける2つのコントラスト関数(h1、h2)を計算する。この(h1、h2)平面の位相が、分域の深さに対応する。これより、結晶の厚さがコヒーレンス長と呼ばれる特性長さの2倍以下のとき、ユニークに3次元分域構造を明らかにすることができるというものである。 この原理を使用して、応用上重要な強誘電体LiNbO3の電場反転を観察することに成功した。パルス電場印加のもとで、分極が逆向きの分域が横および縦方向に楔形に成長することが、明快に観測できた。 この結果は、2001年9月に米国Providennceで開催された、圧電セラミックス日米セミナーでPlenary talkとして招待された。講演後、Prof.Crossなど米国の何人かの教授がこの研究に高い関心をもっていることを知り、うれしく思った。

  • 物質のヘテロ構造ゆらぎと超感受率

    2000   山田 安定, 近 桂一郎, 角田 頼彦, 小山 泰正

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     (1)リラクサーPb(Mg1/3Nb2/3)O3/xPbTiO3について,長距離秩序が大きな経歴依存性を示すこと,また電場を加えると非常に長い緩和時間(一日近くを要することもある)を伴って,長距離秩序度が発達することを見出した。(上江洲)(2)relaxor現象に対して最も核心となると思われる2相共存の問題について、中性子小角散乱実験、及びギンツブルグ-ランダウ理論に基く理論計算を行った。実験についてはrelaxorそのものは小角散乱に寄与しないので、同様の緩和現象を示すMn酸化物系の磁気的2相共存について研究し、この物質中で確かに平均サイズ30nm程度の強磁性クラスターが、反強磁性母相の中に分布していることを確かめた。(山田)(3)電荷秩序型強誘電体YFe2O4で構造相転移での対称性の低下に伴う誘電分散の消失を見出した。(近)(4)強誘電体LuMn2O5では自発分極の出現等の変化に伴って,らせん磁気秩序の伝播ベクトルが変化することを見出した。(近)(5)BaTiO3およびSrTiO3をベースとした,複合ペロブスカイト酸化物セラミックスを作成し,その構造と誘電応答特性を測定した。特にBa1-XLaXTi1-XCrXO(x=0.028) は,室温で3000を越える大きな誘電率と比較的フラットな温度特性、また2%以下の小さな誘電損失をもつことを見出した。これがリラクサーであることは今後さらに評価していかなくてはならないが,開発目標にしていた室温で誘電特性が大きくかつ損失の少ない鉛を含有しない化合物を開発することに成功した。(上江洲、近)(6)Pd及びPtをベースにした3d遷移金属との無秩序合金で、不純物の種類によって原因の異なる、原子やスピンの配列に関する非整合な変調波の短距離秩序を中性子散乱で見つけた。この変調波の波長は不純物の濃度と共に連続的に変化し、母体のフェルミ面の形状の反映と考えられる。(角田)

  • 光屈折効果に関する国際会議

    1996   大頭 仁, 小松 進一, 加藤 勇, 宗田 孝之, 黒田 和男, 富田 康生, S.Odoulov

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     光屈折効果はレーザー光自身が媒質の屈折率を変化させる現象であり、光伝送、画像処理、波面修復、高密度記録などの先端技術サイドから注目を集めている。一方、この効果が示す、低い注入エネルギーで発現するさまざまな光学非線形性のため、基礎科学においても重要な分野となっている。このような背景にたって、1987年より5回の国際会議が2年ごとに米国、欧州で交互に開催され,1997年で第6回を迎える。年々参加者、参加国数が増加しており、この分野の研究の重要性が認識されてきている。そこで1995年にアメリカで開かれた会議に引き続き、この分野の日本の活動の中心の一つである早稲田大学が主催し、早稲田大学における基礎・応用分野の研究者が協力して、アジアでの最初の会議を開催する。アメリカで開催された第5回会議の国際諮問委員会の席上、上江洲はこの会議を早稲田大学で開催することを提案した。その後の国内の議論により、早稲田大学ではこの分野で世界的に活躍している著名な研究者に十分時間をかけて、基礎から最先端の仕事を講演してもらうInvitational Symposiumにすることが決定され、また国際諮問委員会でも承認された。この結果、アメリカのカルフォルニア工科大学のAmnon Yariv教授を含めた14名の招待講演者を決定した。国別にはアメリカ7名、フランス1名、英国1名、ドイツ1名、ウクライナ1名、中国1名、台湾1名、日本1名である。この会議の準備のため、上記国際諮問委員会、組織委員会(委員長、大頭仁早大教授)、プログラム委員会(委員長黒田和男、東大教授)、実行委員会(委員長、上江洲由晃早大教授)を発足させ開催の準備を行ってきた。またウクライナで行なわれた第4回会議の主催者であるProf.S.Odoulvを日本に招聘して意見を聞いた。会議は1997年6月9日と10日の両日、早稲田大学井深大記念ホールで行なわれる。15ケ国から約200名の参加が見込まれる。

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