1998 Fiscal Year Final Research Report Summary
Anomalous Metallic State near the Mott Transition
| Project/Area Number |
07237101
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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 |
FUKUYAMA Hidetoshi University of Tokyo, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (10004441)
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| Co-Investigator(Kenkyū-buntansha) |
TAKURA Yoshinori University of Tokyo, Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (30143382)
SATO Masatoshi Nagotya University, Graduate School of Science, Professor, 理学部, 教授 (40092225)
IMADA Masatoshi University of Tokyo, The Institute for Solid State Physics, Professor, 物性研究所, 教授 (70143542)
MAEKAWA Sadamichi Tohoku University, Institute for Materials Reserach, Professor, 金属材料研究所, 教授 (60005973)
YASUOKA Hiroshi University of Tokyo, The Institute for Solid State Physics, Professor, 物性研究所, 教授 (50026027)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Mott insulator / Anomalous MetalicbState / High TィイD2cィエD2 Cuprates / Pseudo-gap / Mn Oxides / Colossal Magnetresistance / Charge Ordering / Orbitals |
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| Research Abstract |
Mott insulator is the state of matter which is insulating due to strong correlations and is beyond the simple band theory. In this Mott insulator electronic spins survive and various types of magnetism are realized. Once carriers are doped into such Mott insulating state, electric current flows and the metallic state is achieved, in this metallic state the conduction and magnetism interplay in essential ways in sharp contrast to the carrier doping into the band insulators as in the doped semiconductors and hence called the Anomalous Mettalic State(AMS). Actually the high temperature superconductivity realized in cuprates can considered as one of the groudstates of this AMS State. Various intriguing features observed in other transition metal oxides are another aspects of this AMS as well. To elucidate the true nature of AMS both experimentally and theoretically was the target of this research project. The first of the results of 3-years studies toward this direction was the almost comp
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lete experimental identifications of AMS in cuprates including spin-gap or pseudo-gap in underdoped region and anomalous behaviors of Hall coefficient at elevated temperatures. Theoretically it has been clarified that antiferromagnetic fluctuations are playing important roles at high temperatures whereas singlet formations due to the same antiferromagnetic interactions are causing the pseudo-gap at low temperatures. On the other hand in the Manganites, which are most studied among transition metal oxides, the orbital degrees of freedom have been seen to lead to the versatality of both transport and magnetic properties and the causes of colossal magnetoresistance and charge ordering have been identified. Moreover in ruthenides with triply-degenerate orbitals the stability of triplet superconductivity has been confirmed experimentally, which fact has disclosed another novel possibility of quantum fluids with orbital degeneracy. This will be an important step toward deeper understanding of condensed matters. Less
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Research Products
(12 results)
