2007 Fiscal Year Final Research Report Summary
New Phase of Matter in Multidisciplinary Approach
| Project/Area Number |
15GS0213
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| Research Category |
Grant-in-Aid for Creative Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Institution | Osaka University |
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Principal Investigator |
KITAOKA Yoshio Osaka University, Graduate School of Engineering Science, Professor (70110707)
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| Co-Investigator(Kenkyū-buntansha) |
MIAKE Kazumasa Osaka University, Graduate School of Engineering Science, Professor (90109265)
ONUKI Yoshichika Osaka University, Graduate School of Science, Professor (40118659)
SUGA Shigemasa Osaka University, Graduate School of Engineering Science, Professor (40107438)
NOZUE Yasuo Osaka University, Graduate School of Science, Professor (60125630)
SHIMIZU Katsuya Osaka University, Center for Quantum Science and Technology under Extreme Conditions, Professor (70283736)
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| Project Period (FY) |
2003 – 2007
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| Keywords | Materials Science / Strongly correlated matter / Unconventional superconductors / Quantum critical D phenomena / Magnetism / Condensed-matter theory / Condensed-matter exneriment / NMR / NOR |
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| Research Abstract |
Our main objectives have established new concepts in materials science through the elucidation of the new phases of matter that underlies the superconductivity and magnetic ordering in strongly correlated matter, and the creation of unique materials, by measuring the properties of the materials in multidisciplinary approach. We list up the remarkable results obtained by this project.
1. The discovery of the uniformly coexisting phase of antiferromagnetism (AFM) and superconductivity (SC) in a single CuO_2 layer has lead us to uncover their genuine phase diagram including an AF quantum critical point, which significantly differs from the previously believed phase diagrams as the function of carrier doping level for high-T_c copper-oxides superconductors.
2. A tetracritical point in the temperature(T)-pressure(P) phase diagram of the heavy-fermion (HF) compound CeRhIn_5 was unraveled against the previous research results.
3. The coexistence phase of ferromagnetism and SC was identified in UGe_2 around a quantum first-order phase transition.
4. Novel pressure-induced superconductors CeNiGe_3 and Ce_2Ni_3Ge_5 were discovered.
5. The discovery of the pressure-induced SC of HF compounds without inversion symmetry, such as UIr and CeIrSi_3 has pointed to the possibility of a new and unique superconducting state.
6. Miyake, et. al. have been able to explain the appearance of high-T_c SC for HF compounds with the sudden change in the. valence number of Ce upon the application of pressure, by a novel anisotropic SC mechanism triggered by the critical valence number fluctuation.
These remarkable findings on the new phases of strongly correlated matter would lead us to a coherent understanding of the mechanism of unconventional SC in HF compounds and high-T_c superconductors which is a long-term issue since their discoveries.
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