研究者詳細 - 池田　直

論文 - 池田　直

分割表示 209 件中 161 - 180 件目／全件表示 >>

Structural change on the magnetic field-induced insulator-to-metal transition in distorted perovskite Eu<inf>0.6</inf>Sr<inf>0.4</inf>MnO <inf>3</inf>

Shin Nakamura, Shin Nakamura, Susumu Shimomura, Naoshi Ikeda, Shigeki Nimori, Takao Takeuchi, Kikuo Itoh

Journal of the Physical Society of Japan 73 ( 11 ) 3059 - 3063 2004年11月

記述言語：英語出版者・発行元：一般社団法人日本物理学会

Structural feature of Eu0.6Sr0.4MnO3 through the magnetic-field-induced insulator-to-metal (IM) transition has been investigated by X-ray powder diffraction in a magnetic field using synchrotron radiation. No superlattice reflections due to the charge and orbital ordering are detected in the insulator phase down to 20 K. Both of the insulator phase and the induced metal phase are proved to be in orthorhombic structure with Pnma space group, and thus a change of the crystal symmetry is not detected on the IM transition. However, the lattice constants abruptly increase and the reflection intensities abruptly change through the transition. These suggest a rotation of MnO6 octahedron in a manner to increase Mn-O-Mn angles. This structural change is consistent with a gain in electron transfer energy in the double exchange mechanism that stabilizes the metallic and ferromagnetic state. © 2004 The Physical Society of Japan.

DOI： 10.1143/JPSJ.73.3059

Magnetic structure of CoO studied by neutron and synchrotron x-ray diffraction 査読

K Tomiyasu, T Inami, N Ikeda

PHYSICAL REVIEW B 70 ( 18 ) 1 - 6 2004年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

Below T-N=289 K, the antiferromagnet CoO exhibits magnetic long-range order described by a propagation vector along the trigonal axis, whereas the lattice is distorted monoclinicly along both the tetragonal and the trigonal axes. In order to elucidate this inconsistency, we performed neutron and synchrotron x-ray diffraction experiments on single crystals of CoO, and found a series of magnetic reflections represented by a propagation vector along the tetragonal axis below T-N. These results suggest an altered magnetic structure of CoO, which includes both the trigonal and the tetragonal propagation vectors, has a monoclinic symmetry, and which is in accordance with the distorted lattice symmetry.

DOI： 10.1103/PhysRevB.70.184411

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0003-2764-0908

Frustration and ordering of iron ions on triangular iron mixed valence system RFe<inf>2</inf>O<inf>4</inf>

N. Ikeda, H. Ohsumi, M. Mizumaki, S. Mori, Y. Horibe, K. Kishimoto

Journal of Magnetism and Magnetic Materials 272-276 2004年5月

We report a resonant X-ray diffraction and a transmission electron microscope observation on triangular layered oxide RFe2O4 (R = Lu and Y). The observed super structure is concluded to be originated from the charge ordering on triangular plane. The origin of the charge ordering is interpreted as the competing interaction of the charges between nearest and next nearest neighbor charges on triangular lattice. © 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmmm.2003.12.155

Scopus

researchmap

Magnetic field induced phase transition in distorted perovskite Eu <inf>0.6</inf>Sr<inf>0.4</inf>MnO<inf>3</inf>

Shin Nakamura, Shin Nakamura, Susumu Shimomura, Naoshi Ikeda, Masaichiro Mizumaki, Hiroyuki Ohsumi, Shigeki Nimori, Takao Takeuchi, Kikuo Itoh

Journal of Magnetism and Magnetic Materials 272-276 424 - 425 2004年1月

Structural feature of Eu0.6Sr0.4MnO3 through the magnetic field induced insulator-to-metal transition has been investigated by using synchrotron X-ray diffraction in the magnetic field. While keeping the same Pnma symmetry, the lattice constant b jumps at the transition field, which is responsible for magnetoelastic effect. We suggest that the structural change through the transition is a rotation of MnO 6 octahedron in a manner that the Mn-O-Mn angle increases toward 180°. © 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmmm.2003.11.139

Scopus

researchmap

Magnetic behavior of some rare-earth transition-metal perovskite oxide systems

Kenji Yoshii, Akio Nakamura, Masaichiro Mizumaki, Naoshi Ikeda, Jun'ichiro Mizuki

Journal of Rare Earths 22 733 - 738 2004年1月

Relationship between charge stripe order and structural phase transitions in La1.875Ba0.125-xSrxCuO4 査読

H. Kimura, Y. Noda, H. Goka, M. Fujita, K. Yamada, M. Mizumaki, N. Ikeda, H. Ohsumi

Phys. Rev. B 70 ( 13 ) 134512/1 - 134512/8 2004年

Magnetic field induced phase transition in distorted perovskite Eu0.6Sr0.4MnO3 招待

Shin Nakamura, Susumu Shimomura, Naoshi Ikeda

Sprin-8 Research Frontiers 2003 51 - 52 2004年

Structure transition and charge competition on YFe<inf>2</inf>O<inf>4</inf>

Naoshi Ikeda, Ryosuke Mori, Shigeo Mori, Kay Kohn

Ferroelectrics 286 175 - 184 2003年6月

We report the low temperature charge ordered structure and magnetic relaxation in nearly stoichiometric YFe 2 O 4 in which the charge frustration effect is considered to be dominant. The superlattice reflections have revealed the presence of four different phases with a triple, double, quadruple and septuplex charge-superstructure in the temperature range from room temperature to 130 K. The observed successive transitions have been proposed by a previous X-ray powder diffraction study. A slow relaxation of the superstructure was found at 130 K. Time dependence of the magnetic moment was observed at about 240 K to suggest a similar relaxation. © 2003 Taylor & Francis.

DOI： 10.1080/00150190390206356

Scopus

researchmap

Critical phenomena in helical magnet beta-MnO2: X-ray magnetic scattering study 査読

H Sato, Y Kawamura, T Ogawa, Y Murakami, H Ohsumi, M Mizumaki, N Ikeda

PHYSICA B-CONDENSED MATTER 329 757 - 758 2003年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

It has been theoretically expected that critical phenomena of helimagnetism is drastically different from those of collinear antiferromagnetism due to the existence of chiral degree of freedom. In order to verify this prediction, we carried out X-ray magnetic scattering measurements on a simplest helimagnet beta-MnO2 using a synchrotron radiation. The critical exponent beta was estimated at 0.25+/-0.05 from the temperature dependence of the scattering intensity. This value is consistent with the predicted value 0.253 for chiral system rather than with 0.346 for collinear system. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0921-4526(02)02501-2

Web of Science

researchmap

Synchrotron x-ray diffraction study of a charge stripe order in (formula presented)-doped (formula presented) 査読

M. Fujita, H. Kimura, Y. Noda, K. Yamada, H. Goka, N. Ikeda

Physical Review B - Condensed Matter and Materials Physics 67 ( 14 ) 2003年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

Lattice distortions associated with charge stripe order in (formula presented) hole-doped (formula presented) are studied using synchrotron x-ray diffraction for (formula presented) and (formula presented) The propagation wave-vector and charge order correlation lengths are determined with a high accuracy, revealing that the oblique charge stripes in orthorhombic (formula presented) crystal are more disordered than the aligned stripes in tetragonal (formula presented) crystal. The twofold periodicity of lattice modulations along the c axis is explained by long-range Coulomb interactions between holes on neighboring (formula presented) planes. © 2003 The American Physical Society.

DOI： 10.1103/PhysRevB.67.140503

Scopus

researchmap

Review and Prospect of Ferroelectricity and Magnetism in YMn₂O₅ 査読

Yukio Noda, Yoshikazu Fukuda, Hiroyuki Kimura, Isao Kagomiya, S. Matsumoto, Kay Kohn, Takahisa Shobu, Naoshi Ikeda

Journal of the Korean Physical Society 42 S1192 - 1195 2003年4月

Synchrotron x-ray diffraction study of a charge stripe order in 1/8-doped La1.875Ba0.125-xSrxCuO4

H. Kimura, H. Goka, M. Fujita, Y. Noda, K. Yamada, N. Ikeda

Physical Review B - Condensed Matter and Materials Physics 67 ( 14 ) 1405031 - 1405034 2003年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

Lattice distortions associated with charge stripe order in 1/8 hole-doped La1.875Ba0.125-xSrxCuO4 are studied using synchrotron x-ray diffraction for x = 0.05 and x = 0.075. The propagation wave-vector and charge order correlation lengths are determined with a high accuracy, revealing that the oblique charge stripes in orthorhombic x = 0.075 crystal are more disordered than the aligned stripes in tetragonal x = 0.05 crystal. The twofold periodicity of lattice modulations along the c axis is explained by long-range Coulomb interactions between holes on neighboring CuO2 planes.

Scopus

researchmap

Synchrotron x-ray diffraction study of a charge stripe order in 1/8 -doped La_1.875Ba_0.125-xSr_xCuO₄

H. Kimura, H. Goka, M. Fujita, Y. Noda, K. Yamada, N. Ikeda

Phys. Rev. B 67 140503(1)-140503(3) 2003年

Study of 2D phase transition of polar organic dye molecules at the air-water interphase by using grazing-incidence x-ray diffraction

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

Ferroelectrics 286 921 - 926 2003年

掲載種別：研究論文（国際会議プロシーディングス）

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. © 2003 Taylor & Francis.

DOI： 10.1080/00150190390206374

Scopus

researchmap

Ground state of NaV₂O₅ under high pressure

K. Ohwada, J. Muraoka, Y. Fujii, H. Nakao, Y. M. Murakami, Y. Noda, N. Ikeda, H. Ohsumi, M. Isobe, Y. Ueda

SPring-8 User Experiment Report 10 14 - 14 2003年

Lattice Distortion at Ferroelectric Transition of YMn₂O₅

I. Kagomiya, S. Mat.sumoto, K. Kohn, Y. Fukuda, T. Shobu, H. Kimura, Y. Noda, N. Ikeda

Ferroelectrics 286 167 - 174 2003年

Improvement of experimental technology at high pressure and low temperature and the observation of superlattice reflections of K₃H(SO₄)₂ at high pressure

Takahisa Shobu, M. Mizumaki, Hiroyuki Ohsumi, Naoshi Ikeda, Yukio Noda

SPring-8 User Experiment Report 11 357 - 357 2003年

Ground state of NaV₂O₅ under high pressure 2

K. Ohwada, Y. Fujii, H. Nakao, Y. M. Murakami, Y. Noda, N. Ikeda, H. Ohsumi, M. Isobe, Y. Ueda

SPring-8 User Experiment Report 11 22 - 22 2003年

Ordered charge asphericity around dysprosium and structural deformation in DyB2C2 査読

H Adachi, H Kawata, M Mizumaki, T Akao, M Sato, N Ikeda, Y Tanaka, H Miwa

PHYSICAL REVIEW LETTERS 89 ( 20 ) 206401 2002年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

The oribitally ordered phase of DyB2C2 has been studied by nonresonant x-ray diffraction with high-brilliance synchrotron radiation. From the condition of diffraction, the symmetry property of the charge distribution around dysprosium has been concluded at the quadrupolar level. The quantitative inspection, furthermore, indicates that the observed signals cannot be interpreted as arising only from the 4f electrons of dysprosium responsible for the ordering; instead, the experiment can be described rather well by considering a distortion of the metaloid network concomitant with the ordering.

DOI： 10.1103/PhysRevLett.89.206401

Web of Science

researchmap

Symmetry breaking in the metal-insulator transition of BaVS<inf>3</inf>

T. Inami, K. Ohwada, H. Kimura, M. Watanabe, Y. Noda, H. Nakamura, T. Yamasaki, T. Yamasaki, M. Shiga, N. Ikeda, Y. Murakami, Y. Murakami

Physical Review B - Condensed Matter and Materials Physics 66 731081 - 731084 2002年8月

It has been believed for a long time that the metal-to-insulator (MI) transition of BaVS3 is not accompanied by any spatial order of the spin and lattice. We have carried out x-ray-diffraction measurements of BaVS3 single crystals using a laboratory x-ray source as well as synchrotron radiation, and found that superlattice reflections which double the lattice constant c exist below the transition temperature. The most probable space group at the low-temperature insulator phase contains two inequivalent vanadium sites, and thus a charge disproportionation of the vanadium ions is considered the main cause of the MI transition.

DOI： 10.1103/PhysRevB.66.073108

Scopus

researchmap

　前のページ - 次のページ　

<池田 直>

論文 - 池田 直

<池田　直>

論文 - 池田　直