Yoshiaki Uesu

Waseda University

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J. Kobayashi

Waseda University

Hiroko Yokota

Nagoya University

Noritaka Kato

Meiji University

B. A. Strukov

Lomonosov Moscow State University

Shutaro Asanuma

National Institute of Advanced Industrial Science and Technology

Sunao Kurimura

National Institute for Materials Science

Junichi Kaneshiro

RIKEN Center for Biosystems Dynamics Research

Charlotte Malibert

École Centrale Paris

Jean‐Michel Kiat

CentraleSupélec

Mamoru Fukunaga

Okayama University

Cooperative Institutions

Waseda University

109

Tohoku University

The University of Tokyo

Centre National de la Recherche Scientifique

Nagoya University

Tokyo Institute of Technology

Osaka University

National Institute of Advanced Industrial Science and Technology

Kyoto University

École Centrale Paris

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Switching Processes and Formation of the Stable Artificial Domain Structure in Ferroelectric LaBGeO₅

Ferroelectrics (2005)

B. A. Strukov E. V. Milov V. N. Milov A. P. Korobtsov Toshiro Tomida

The processes of polarization switching in LaBGeO 5 (LBGO) crystals are studied in details for the triangle and pulse electric field in the wide temperature range from room temperature (RT) to Tc = 530°C. It is revealed that the temperature dependence of a coercive field (f = 0.1 Hz) has an exponential form and this field reaches a value 150 kV/cm at the RT. The temperature evolution of the switching time and the form of the switching current are obtained in the mode of the successive solitary pulses and in the steady conditions. The features of "non-classical" behavior are noted (the dependence of switching parameters on the prehistory of samples, frequency dependence of the switching time). It is shown that the stable artificial domain structure at RT with the periodicity of 200 μm can be obtained by applying about 300–350 V/mm near 300°C. The stable domain structure was contrasted by means of SHG microscope probing.

Atmospheric temperature range

10.1080/00150190590926247

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Citations (15)

X-Ray dilatometric study of the phase transition of the improper ferroelectrics KH₂PO₄and KD₂PO₄

Ferroelectrics (1974)

Yoshiaki Uesu T. Tanaka J. Kobayashi

Abstract X-ray dilatometric measurements were made on lattice strains of KH2PO4 and KD2PO4 as a function of temperature and biasing electric field near the Curie point. The electrostriction contained in the lattice strains x1, x2 along the a-and b-axes cannot be explained in terms of the ordinary electrostrictive effect. In order to interpret these new effects, the phenomenological theory of improper ferroelectrics has been successfully applied. The difference of the transition mechanism between KH2PO4 and KD2PO4 is discussed from the same viewpoint of improper ferroelectrics.

Electrostriction

Lattice (music)

10.1080/00150197408238010

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Citations (18)

Optical and x-ray studies on the low-temperature phase transition of

Journal of Physics Condensed Matter (1996)

K. Fujishiro Yoshiaki Uesu

Low-temperature phase transitions of with non-stoichiometric composition were investigated using a polarization microscope and x-ray diffractometer. Both apparatuses were equipped with a specially designed low-temperature cryostat which enabled us to measure the birefringence down to 4 K and x-ray reflections down to 20 K. Ferroelastic domain structure was observed to persist even at 4 K. Birefringence and pure shear show a peak at about 200 K and drop steeply at 110 K but do not vanish below 110 K. These facts indicate that the phase below 110 K is not re-entrant to the tetragonal 4 mm phase. The quite long relaxation process observed in birefringence and the appearance of a new reflection in the x-ray diffraction experiment indicate that the quasi-tetragonal region appears at 110 K and develops with long relaxation time.

Tetragonal crystal system

Polarization Microscopy

Diffractometer

10.1088/0953-8984/8/35/012

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Citations (10)

Optical activity of ferroelectric liquid crystal DOBAMBC

Ferroelectrics (1981)

Yoshiaki Uesu J. Kobayashi Takuji Matsumoto B. A. Strukov Takahiro Kawabe

Abstract The optical activity of DOBAMBC was successfully measured by using the high accuracy universal polarimeter. It is revealed that the smectic A phase is optical active. Temperature dependence of the gyration and electrogyration coefficients in the smectic C phase are also measured.

Polarimeter

Gyration

10.1080/00150198108219627

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Citations (6)

Ferroelectricity and Ferromagnetism of BaTiO₃/BaFeO₃Superlattice Thin Films

Japanese Journal of Applied Physics (2012)

Ryosuke Fukatani Hiroko Yokota S. Ogura Yoshiaki Uesu Ausrine Bartasyte

Ferroelectric BaTiO3 and antiferromagnetic BaFeO3 are deposited alternatively by a pulsed laser deposition method with the aim of fabricating room-temperature multiferroic materials. X-ray diffraction (XRD) analysis reveals that the superlattice structure is fabricated with a designed periodicity and thin film quality is improved by increasing BaFeO3 layers. Ferroelectricity and ferromagnetic properties are examined by the double-wave method (DWM) of D–E hysteresis loops, an XRD dilatometry, and a superconducting quantum interference device magnetometer. Our superlattice thin film shows multiferroicity, i.e., the coexistence of ferroelectricity and ferromagnetism, at room temperature.

Pulsed Laser Deposition

Hysteresis

Ferromagnetic material properties

10.7567/jjap.51.09lb01

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Citations (2)

X-Ray Dilatometric Study of Phase Transitions of Ferroelectric (NH₄)₂BeF₄

De Gruyter eBooks (1981)

Yoshiaki Uesu J. Ogawa N. Hanami B. A. Strukov J. Kobayashi

10.1515/9783112501047-041

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Citations (0)

Study of the phase transitions to the incommensurate phase in (NH₄)₂BeF₄(AFB) crystals

Ferroelectrics Letters Section (1984)

B. A. Strukov P. S. Smirnov S. A. Taraskin Yoshiaki Uesu

Abstract Specific heat high resolution data for AFB crystals are presented. The effect of SO4 2-ions impurities and γ-irradiation upon the hysteresis phenomena in AFB crystals is discussed.

10.1080/07315178408202414

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Citations (3)

Photorefractive Response Characteristics and Generation of Phase-Conjugate Wave in Bi₁₂GeO₂₀ and Bi₁₂SiO₂₀ Crystals

Japanese Journal of Applied Physics (1993)

Toshiyuki Yoshihara Yoshiaki Uesu Kazuyasu Hikita Hiroyuki Iizuka

The response time of the photorefractive effect in Bi 12 GeO 20 was evaluated for the first time using nearly degenerate two-wave mixing. The result was analyzed in the context of the charge transport theory and the trap density was determined as N A =2.4×10 21 m -3 . It was also found that an optimum amplitude of the displacement of the piezomirror exists in the moving-grating method. By adopting this amplitude, the reflectivities of the phase-conjugate wave reached 490% and 430% for Bi 12 SiO 20 and Bi 12 GeO 20 , respectively.

Phase conjugation

Conjugate

10.1143/jjap.32.4296

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Citations (2)

Reversible Thermochromic Transition between Different J-Aggregate States of Amphiphilic Merocyanine Dye Crystallites

MRS Proceedings (2000)

Noritaka Kato Yasuaki Shin Yoshiaki Uesu

Thermochromism

J-aggregate

Merocyanine

10.1557/proc-660-jj5.33

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SHG Spectroscopy and SHG Images of Merocyanine J-Aggregate Monolayer at the Air-Water Interface

Molecular crystals and liquid crystals science technology. Section A, Molecular crystals and liquid crystals/Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals (2000)

Kentaro Saito Noritaka Kato Yoshiaki Uesu

Abstract Optical second harmonic generation (SHG) spectra and SHG images were investigated on merocyanine dye (MD)/arachidic acid mixed monolayer at the air-water interface. A sharp peak of the SHG spectrum was observed at the J-band of 620nm. In the low wavelength region below 400nm, a sharp increase of the SHG spectrum was also observed. Careful comparisons of SHG images taken at several wavelengths revealed that the whole spectrum originates from the J-aggregate states of MD.

Merocyanine

Arachidic acid

10.1080/10587250008024876

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Citations (0)