JOPSS - Search Results

Journal Articles

Dielectric properties and lattice dynamics of Ca-doped K $_{0.95}$ Li $_{0.05}$ TaO $_{3}$

Wakimoto, Shuichi; Samara, G. A.*; Grubbs, R. K.*; Venturini, E. L.*; Boatner, L. A.*; Xu, G. Y.*; Shirane, Gen*; Lee, S.-H.*

Physical Review B, 74(5), p.054101_1 - 054101_12, 2006/08

https://doi.org/10.1103/PhysRevB.74.054101

Times Cited Count：25 Percentile：69.03(Materials Science, Multidisciplinary)

Relaxor behavior and lattice dynamics have been studied for a single crystal of K $_{1-x}$ LiTaO , where a small amount of a Ca impurity ( ppm) is incorporated. The dielectric measurements revealed Debye-like relaxations of Li dipoles and the Li-Li dipolar pairs below 200K. In the neutron scattering, diffuse scattering appears around the nuclear Bragg peaks below K and phonon line broadening features start to appear at even higher temperatures suggesting that polar nano-regions (PNR's) start to form at these temperatures accomapied with the relaxational behavior of Li ions. From analyses of the diffuse intensities, the displacements include a uniform phase shift of all of the atoms in addition to the atomic displacements corresponding to a polarization vector of the transverse optic soft ferroelectric mode, a finding that is analogous to that in the prototypical relaxor material PMN.

Journal Articles

Incommensurate lattice distortion in the high temperature tetragonal phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$

Wakimoto, Shuichi; Kimura, Hiroyuki*; Fujita, Masaki*; Yamada, Kazuyoshi*; Noda, Yukio*; Shirane, Gen*; Gu, G.*; Kim, H.*; Birgeneau, R. J.*

Journal of the Physical Society of Japan, 75(7), p.074714_1 - 074714_6, 2006/07

https://doi.org/10.1143/JPSJ.75.074714

Times Cited Count：25 Percentile：72.83(Physics, Multidisciplinary)

We report incommensurate diffuse (ICD) scattering appearing in the high-temperature-tetragonal (HTT) phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$ with observed by the neutron diffraction technique. For all compositions, a sharp superlattice peak of the low-temperature-orthorhombic (LTO) structure is replaced by a pair of ICD peaks with the modulation vector parallel to the CuO octahedral tilting direction, that is, the diagonal Cu-Cu direction of the CuO plane, above the LTO-HTT transition temperature . The temperature dependences of the incommensurability for all samples scale approximately as , while those of the integrated intensity of the ICD peaks scale as $(T-T_s)^{-1}$ . These observations together with absence of ICD peaks in the non-superconducting sample evince a universal incommensurate lattice instability of hole-doped 214 cuprates in the superconducting regime.

Journal Articles

Frustrating interactions and broadened magnetic excitations in the edge-sharing CuO $_{2}$ chains in La $_{5}$ Ca $_{9}$ Cu $_{24}$ O $_{41}$

Matsuda, Masaaki; Kakurai, Kazuhisa; Lorenzo, J. E.*; Regnault, L. P.*; Hiess, A.*; Shirane, Gen*

Physical Review B, 68(6), p.060406_1 - 060406_4, 2003/08

https://doi.org/10.1103/PhysRevB.68.060406

Times Cited Count：21 Percentile：67.27(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Neutron diffraction study of field-cooling effects on the relaxor ferroelectric Pb[(Zn $_{1/3}$ Nb $_{2/3}$ ) $_{0.92}$ Ti $_{0.08}$ ]O

Owada, Kenji; Hirota, Kazuma*; Rehrig, P. W.*; Fujii, Yasuhiko*; Shirane, Gen*

Physical Review B, 67(9), p.094111_1 - 094111_8, 2003/03

https://doi.org/10.1103/PhysRevB.67.094111

Times Cited Count：105 Percentile：94.38(Materials Science, Multidisciplinary)

High-temperature () and high-electric-field () effects on Pb[(Zn $_{1/3}$ Nb $_{2/3}$ ) $_{0.92}$ Ti $_{0.08}$ ]O $_{3}$ (PZN-8%PT) were studied comprehensively by neutron diffraction in the ranges ~K and ~kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field cooling process (FC, ~kV/cm), a successive cubic (C) tetragonal (T) monoclinic (M $_{rm C}$ ) transition was observed. In the zero field cooling process (ZFC), however, we have found that the system does transform to the rhombohedral (R) phase as widely believed, but to a new, unidentified phase, which we call X. X gives a Bragg peak profile similar to that expected for R, but the -axis is always slightly shorter than the -axis. As for field effects on the X phase, it transforms into the M $_{rm C}$ phase via another monoclinic phase (M $_{rm A}$ ) as expected from a previous report [Noheda , 224101 (2002)].

Journal Articles

Magnetic field effects and magnetic anisotropy in lightly doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Matsuda, Masaaki; Fujita, Masaki*; Yamada, Kazuyoshi*; Birgeneau, R. J.*; Endo, Yasuo*; Shirane, Gen*

Physical Review B, 66(17), p.174508_1 - 174508_6, 2002/11

https://doi.org/10.1103/PhysRevB.66.174508

Times Cited Count：11 Percentile：49.59(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Electronic phase separation in lightly doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Matsuda, Masaaki; Fujita, Masaki*; Yamada, Kazuyoshi*; Birgeneau, R. J.*; Endo, Yasuo*; Shirane, Gen*

Physical Review B, 65(13), p.134515_1 - 134515_6, 2002/04

https://doi.org/10.1103/PhysRevB.65.134515

Times Cited Count：141 Percentile：96.41(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Neutron scattering studies on lightly-doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Matsuda, Masaaki; Birgeneau, R. J.*; Endo, Yasuo*; Fujita, Masaki*; Hiraka, Haruhiro*; Kastner, M. A.*; Shirane, Gen*; Wakimoto, Shuichi*; Yamada, Kazuyoshi*

Journal of the Physical Society of Japan, Vol.70, Supplement A, p.46 - 48, 2001/05

no abstracts in English

Oral presentation

Incommensurate lattice distortion in the high temperature tetragonal phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$

Wakimoto, Shuichi; Kimura, Hiroyuki*; Fujita, Masaki*; Yamada, Kazuyoshi*; Noda, Yukio*; Shirane, Gen*; Gu, G.*; Kim, H.*; Birgeneau, R. J.*

no journal, ,

We report incommensurate diffuse (ICD) scattering appearing in the high-temperature-tetragonal (HTT) phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$ with 0.07 0.20 observed by the neutron diffraction technique. For all compositions, a sharp superlattice peak of the low-temperature-orthorhombic (LTO) structure is replaced by a pair of ICD peaks with a modulation vector parallel to the CuO octahedral tilting direction, that is, the diagonal Cu-Cu direction of the CuO plane, above the LTO-HTT transition temperature . The temperature dependences of incommensurability for all samples scale approximately to , while those of integrated intensity of the ICD peaks scale to . Those observations together with absence of ICD peaks in the non-superconducting sample evince a universal incommensurate lattice instability of hole-doped 214 cuprates in the superconducting regime.

Oral presentation

Neutron scattering study of lattice dynamics and diffuse scattering in relaxor KLT

Wakimoto, Shuichi; Samara, G. A.*; Grubbs, R. K.*; Venturini, E. L.*; Boatner, L. A.*; Xu, G. Y.*; Shirane, Gen*; Lee, S.-H.*

no journal, ,

Neutron scattering has been performed on relaxor K $_{1-x}$ Li $_{x}$ TaO $_{3}$ (KLT) single crystals to study phonon and duffuse scattering. Dielectric measurements show that the sample has only relaxor state down the base temperature while the sample has a clear ferroelectric transition at K below which the system still shows relaxation of Li ions. Neutron scattering results demonstrate that the transiverse optic ferrolectric mode softens gradually with decreasing temperature for the former sample. On the other hand, the latter sample exhibits small hardening of the TO mode at Tc and then softens below Tc. These facts imply that the TO mode plays an important role in addition to the Li relaxation.

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Dielectric properties and lattice dynamics of Ca-doped K $_{0.95}$ Li $_{0.05}$ TaO $_{3}$

Incommensurate lattice distortion in the high temperature tetragonal phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$

Frustrating interactions and broadened magnetic excitations in the edge-sharing CuO $_{2}$ chains in La $_{5}$ Ca $_{9}$ Cu $_{24}$ O $_{41}$

Neutron diffraction study of field-cooling effects on the relaxor ferroelectric Pb[(Zn $_{1/3}$ Nb $_{2/3}$ ) $_{0.92}$ Ti $_{0.08}$ ]O

Magnetic field effects and magnetic anisotropy in lightly doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Electronic phase separation in lightly doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Neutron scattering studies on lightly-doped La $_{2-x}$ Sr $_{x}$ CuO $_{4}$

Incommensurate lattice distortion in the high temperature tetragonal phase of La $_{2-x}$ (Sr,Ba) $_{x}$ CuO $_{4}$

Neutron scattering study of lattice dynamics and diffuse scattering in relaxor KLT