2005 Fiscal Year Final Research Report Summary
X-ray scattering study on charge-and-orbital correlations and phase separation under extreme conditions
| Project/Area Number |
15540350
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | KEIO UNIVERSITY |
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Principal Investigator |
SHIMOMURA Susumu Keio University, Faculty of Science and Technology, Instructor, 理工学部, 講師 (00260216)
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| Project Period (FY) |
2003 – 2005
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| Keywords | x-ray scattering / charge order / orbital order / insulator-metal transition / magnetic field / high pressure / manganese oxide / electrical resistivity |
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| Research Abstract |
This research focuses on studying phase transitions associated with charge and orbital ordering by means of x-ray scattering in a magnetic field or under high pressure. Main results are as follows.
1.Structural changes through an insulator-metal transition induced by a magnetic field have been investigated in a perovskite-type manganese oxide Eu_<0.6>Sr_<0.4>MnO_3 by x-ray diffraction. The change in the Mn-O-Mn bond angle through the transition qualitatively agrees with the double exchange mechanism. The pressure effect was also studied in a compound exhibiting the charge and orbital ordering. Pressure-induced phase transition to a disordered phase was found. In addition, an indication of the transition to a different type of the charge and orbital ordering was found.
2.X-ray powder diffraction experiments using synchrotron radiation were conducted in a mixed valence system of Fe_2BO_4. The structural properties associated with the charge ordering were analyzed by the Rietveld method.
3.The electrical resistivity of RNiC_2 compounds, where R is rare-earth, shows anomalous temperature dependences. A set of satellite reflections was found below the metal-insulator transition temperature. This result suggests that the charge density wave is developed below the transition temperature.
4.X-ray intensity fluctuation spectroscopy experiments using coherent x-rays were carried out at SPring-8. Speckle patterns were observed in a sample exhibiting an order-disorder transition.
5.X-ray diffraction experiments under high magnetic fields using synchrotron radiation (SPring-8) have been performed in low-dimensional systems and materials with multipole order.
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[Journal Article] Direct and quantitative determination of the orbital ordering in CeB_6 by X-ray diffraction2004
Author(s)
Y.Tanaka, U.Staub, K.Katsumata, S.W.Lovesey, J.E.Lorenzo, Y.Karumi, V.Seagnoli, S.Shimomura, Y.Tabata, Y.Onuki, Y.Kuramoto, A.Kikkawa, T.Ishikawa, H.Kitamura
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Journal Title
Europhysics Letters 68
Pages: 671-677
Description
「研究成果報告書概要(和文)」より
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[Journal Article] Observation of a lattice instability at the field-induced phase transition of the spin-gapped compound Cu_2 (C_5H_12N_2)_2Cl_42004
Author(s)
J.E.Lorenzo, K.Katsumata, Y.Narumi, S.Shimomura, Y.Tanaka, M.Hagiwara, H.Mayaffre, C.Berthier, O.Piovesana, T.Ishikawa, H.Kitamura
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Journal Title
Physical Review B 69
Pages: 220409
Description
「研究成果報告書概要(和文)」より
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[Journal Article] 「研究成果報告書概要(欧文)」より2004
Author(s)
Y.Tanaka, U.Staub, K.Katsumata, S.W.Lovesey, J.E.Lorenzo, Y.Narumi, V.Scagnoli, S.Shimomura, Y.Tabata, Y.Onuki, Y.Kuramoto, A.Kikkawa, T.Ishikawa, H.Kitamura
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Journal Title
Europhysics Letters 68
Pages: 671-677
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[Journal Article] Synchrotron X-ray Diffraction Studies of the Incommensurate Phase of a Spin-Peierls System CuGeO_3 in Strong Magnetic Fields2004
Author(s)
Y Narumi, K.Katsumata, Y.Tabata, S.Kimura, Y.Tanaka, T.Nakamura, S.Shimomura, M.Matsuda, I.Harada, Y.Nishiyama, T.Ishikawa, H.Kitamura, T.Hara, T.Tanaka, K.Tamasaku, M.Yabashi, S.Goto, H.Ohashi, K.Takeshita, T.Ohata, T.Matsushita, T.Bizen
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Journal Title
J.Phys.Soc.Jpn. 73
Pages: 2650-2653
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Observation of a lattice instability at the field-induced phase transition of the spin-gapped compound Cu_2(C_5H_<12>N_2)_2Cl_42004
Author(s)
J.E.Lorenzo, K.Katsumata, Y.Narumi, S.Shimomura, Y.Tanaka, M.Hagiwara, H.Mayaffre, C.Berthier, O.Piovesana, T.Ishikawa, H.Kitamura
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Journal Title
Phys.Rev.B 69
Pages: 220409
Description
「研究成果報告書概要(欧文)」より
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