1997 Fiscal Year Final Research Report Summary
"Exploratory Materials and Properties of 3d Transition Metal Oxides with Mott Transitions"
| Project/Area Number |
07237103
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Research Institution | University of Tokyo |
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Principal Investigator |
TOKURA Yoshinori Univ. Tokyo, Dept. Applied Phys. / Professor, 大学院・工学系研究科, 教授 (30143382)
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| Co-Investigator(Kenkyū-buntansha) |
KUMAGAI Kenichi Hokkaido Univ., Dept. Phys. / Professor, 理学部物理学科, 教授 (70029560)
YASUOKA Hiroshi Univ. Tokyo, ISSP / Professor, 物性研究所, 教授 (50026027)
FUJIMORI Atsushi Univ. Tokyo, Dept. Dept. Phys. / Associate Professor, 大学院・理学科研究室, 助教授 (10209108)
YOSHIZAWA Hideki Univ. Tokyo, ISSP / Associate Professor, 物性研究室, 助教授 (00174912)
TANAKA Mikio Kyoto Univ., Chem. Res. Inst.. / Professor, 化学研究所, 教授 (70068138)
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| Project Period (FY) |
1992 – 1997
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| Keywords | Mott transition / perovskite / colossal magnetoresistance / 3d trandition metal oxide / metal-insulator transition / charge ordering / spin ladder / orbital orderin |
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| Research Abstract |
The aim of this project was to perform systematic and comprehensive study on the Mott transition as well as on the anomalous metallic state near it for 3d electron transition metal oxides and chalogenides.
As a prototype of the filling-control Mott transition, the perovskite-type Ti-oxides have been investigated by measurements of electronic specific heat, optical spectra, photoemission spectra, and NMR to reveal the quantum critical features near the Mott transition, in particular on strongly mass-renormalized metallic states.
The perovskite-type Mn-oxides, that are attracting great current interest in the light of colossal magnetoresitance (CMR) effect, are viewed as another prototype of the Mott transition system. In this project, the interrelation among the spin, charge, and orbital (lattice) dynamics has been extensively investigated by various experimental means. In particular, the presence of the anomalous metallic state relevant to the orbital dynamics has for the first time been pointed out in the present study.
The charge ordering or concomitant charge/orbital ordering is one of generic features for the correlated electron. The phenomena have been investigated for the Mn-oxides and Ni-oxides by measurements of neutron scattering, transport , and optical properties as well as by unrestricted Hartree-Fock calculations to clarify the interrelation among the spin, charge, and orbital sectors.
Many spin-gap systems possibly relevant to Mott transition and superconductivity have been innovated in this project and extensively investigated by magentic (NMR and neutron scattering) measurements.
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