| Project/Area Number |
07237102
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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 |
IMADA Masatoshi Univ. of Tokyo, Inst. for Solid State Physics, Professor, 物性研究所, 教授 (70143542)
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| Co-Investigator(Kenkyū-buntansha) |
KURODA Yoshihiro Univ. Nagoya, Graduate School of Science, Professorof Tokyo, Inst. for Solid State Physics, Professor, 大学院・理学研究科, 教授 (60013504)
KURAMOTO Yoshio Tohoku Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (70111250)
OGATA Masao Univ. Tokyo, Graduate School of Arts and Science, Professor, 総合文化研究所, 助教授 (60185501)
TERAKURA Kiyoyuki National Institute for Advanced Interdisplinary Reseach, Principal researcher, 首席研究官
KOTANI Akio Univ. of Tokyo, Inst. for Solid State Physics, Professor, 物性研究所, 教授 (90029504)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Mott transition / transition metal oxide / strongly correlated slectron systems / cuprate high-TィイD2cィエD2 superconductors / quantum critical phenomena / orbital degenerary effect / incoherent metals / non-fermi liquid |
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| Research Abstract |
Theoretical studies of our project on d-electron systems near Mott-insulator-metal transitions have reached a number of achievements. The central subject of our project is metal-insulator transitions or Mott transitions, where we have found a new universality class with a large dynam-ical exponent. We have found that strong momentum dependent renormalization induces singular renormalization. The anomalous feature of the transition is successfully described by synergy effects between spin/orbital fluctuations and momentum degeneracy. With our clarification of singular momentum dependence due to low dimensionality and resultant incoherent charge dynamics, theoretical understanding of the quantum phase transition for the Mott phenomena has entered a new stage. Another important subject in our research was studies on complex properties in d-electron systems. For instance, in Mn oxides, entanglement and interplay among strong cor-relation effects, spin/orbital degeneracy, Jahn-Teller effect
… More
have been studied in a realistic way as much as possible. Through first principles methods and model calculations, experimental results on spin/orbital/charge orderings and lattice distortions in metals and insulators have successfully been compared. Studies on cuprate superconductors have also made progress. Various approaches such as slave boson methods in the t-J models, 1/N expansion, spin fluctuation theory and numerical methods for correlated fermions have been applied to two-dimensional models with many new pro-posals and concepts to interpret experimental results. Although the consensus on the mechanism of superconductivity has not been reached yet, models to describe the Mott insulator, underdoped and overdoped metals have been proposed on a unified framework. Important progress in under-standing on quantum magnetism in the Mott insulator has also been achieved, especially on the competition between the singlet spin-gapful and the antiferromagnetic phases. Ladder compounds have also been studied intensively. Less
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