2004 Fiscal Year Final Research Report Summary
THEORETICAL STUDIES ON MANY-BAND EFFECTS ON SUPERCONDUCTIVITY AND MAGNETISM IN MOLECULAR CRYSTALS
| Project/Area Number |
15550010
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | KANAZAWA UNIVERSITY |
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Principal Investigator |
NAGAO Hidemi KANAZAWA UNIVERSITY, GRADUATE SCHOOL OF NATURAL SCIENCE AND TECHNOLOGY, ASSOCIATE PROFESSOR, 自然科学研究科, 助教授 (30291892)
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| Project Period (FY) |
2003 – 2004
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| Keywords | superconductivity / many-gap superconductivity / magnetism / crystal structure / many band system / effective electron interactions / electron-phonon interaction / electron pair scattering process |
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| Research Abstract |
Many bands play an important role of many gap superconductivity such as MgB_2 superconductor. Form viewpoint of the importance of many-band, we have theoretically investigated new physical properties such as superconducting gaps etc. arising from many-band. Our purposes of this project are (1) to investigate many-band effects on superconductivity, (2) to investigate many-band effects on magnetism and to discuss the possibility of new magnetic properties, and (3) to investigate many-band effects in molecular crystals. In this project, we have investigated many-band effects on superconductivity and magnetism by using Green's function techniques and some many-band models.
In many-band effects on superconductivity, we have obtained that the superconducting gap in namy-band systems becomes more stable than that of single band systems. The transition temperature for many-band superconductivity becomes higher than that of single band superconductivity. An effective two-electron pair scattering
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process between bands has a very important role to apper many-band superconductivity. We also have investigated a cooperative mechanism for superconductivity with the pair electron scattering process and the effective electron interactins from electron-phonon interaction. In a single band model such as BCS model, the effective electron interaction should be negative. However, In many-band systems, many-band superconductivity appears, even if the effective electron interaction becomes positive or negative.
In many-band effects on magnetism, we have found that effective electron-electron interaction becomes ferromagnetic at half-filling in many-band systems and that antiferromagnetic interaction appears by hole-doping into the many-band systems.
We have investigated magnetic and superconducting properties of herringbone and two-layer square lattices in organic crystals. In the two-layer square lattice, we have obtained that we can expect interesting magnetic properties by many-band effects and have also found the possibilities of many-band superconductivity in such two-layer lattices. Less
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[Journal Article] Spin and pseudo spins in theoretical chemistry. A unified view for superposed and entangled quantum systems2003
Author(s)
K.Yamaguchi, M.Nakano, H.Nagao, M.Okumura, S.Yamanaka, T.Kawakami, D.Yamaki, M.Nishino, Y.Shigeta, Y.Kitagawa, Y.Takano, M.Takahata, R.Takeda
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Journal Title
Bull Korean Chemical Society 24
Pages: 864-880
Description
「研究成果報告書概要(和文)」より
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[Journal Article] Spin and pseudo spins in theoretical chemistry. A unified view for superposed and entangled quantum systems2003
Author(s)
K.Yamaguchi, M, Nakano, H.Nagao, M.Okumura, S.Yamanaka, T.Kawakami, D.Yamaki, M.Nishino, Y.Shigeta, Y.Kitagawa, Y.Takano, M.Takahata, R.Takeda
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Journal Title
B.Kor.Chem.Soc. 24(6)
Pages: 864-880
Description
「研究成果報告書概要(欧文)」より
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[Book] 「物性量子化学入門」第7章2004
Author(s)
山口兆, 吉岡泰規, 中野雅由, 長尾秀実, 奥村光隆
Total Pages
128-146
Publisher
編講談社サイエンティフィク
Description
「研究成果報告書概要(和文)」より
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