2001 Fiscal Year Final Research Report Summary
Charge-Orbital Ordered States in Manganese Oxides studied by High Resolution Electron Microscopy
| Project/Area Number |
11440104
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
YAMAMOTO Naoki Tokyo Institute of Technology, Physics Department, Assoc. Professor, 大学院・理工学研究科, 助教授 (90108184)
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| Co-Investigator(Kenkyū-buntansha) |
MORI Shigeo Osaka Prefecture University, Dept. Materials Science, Assoc. Professor, 総合科学部, 助教授 (20251613)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Manganese oxides / Correlated electron system / transition metal oxide / Nano-structure / Charge order / colossal magneto resistance / Lorenz electron microscopy / magnetic structure |
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| Research Abstract |
Manganese oxides show several characteristic properties such as metal-insulator phase transition, colossal magneto resistance and charge-orbital ordered phases due to strong interactions among charge/orbitals of d electrons, their spin system, and lattice system, Recently by transmission electron microscopy we found the coexistence of the charge ordered (CO) phase and ferromagnetic metal (FM) phase, which are closely related to the colossal magneto resistance and charge-orbital ordered phases. In the present study we investigated nano-structure of the phase separated state and charge/orbital ordered structure using a high resolution transmission electron microscope and Lorenz electron microscope. We observed the coexistence of the CO phase and FM phase in La_<1-x>Ca_xMnO_3, and found that the paired Jahn-Teller stripes (PJTS) play an important role in forming nano-structures of the coexistence state. The effect of substitution of the Mn site with Cr ion is also studied. Lorenz electron microscope reveals that large domains of FM phase and CO phase coexist on a micrometer scale in (La_<5/8-x>Pr_x)Ca_<3/8>MnO_3.
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[Publications] A. Machida, Y. Moritomo, S. Mori, N. Yamamoto, K. Ohoyama, E. Nishibori, M. Takata, M. Sakata, T. Otomo, and A. Nakamura: "Microscopic charge separation in Tb_<1-x>Ca_xMnO_3 (x〜1)"J. Phys. Soc. Jpn.. 71, 27. (2002)
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