| Project/Area Number |
17K05528
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
浅岡 類 東北大学, 工学研究科, 助教 (60780947)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 銅酸化物超伝導 / T'型構造 / 擬ギャップ状態 / 電荷密度波 / 擬ギャップ / 交替フラックス状態 / 高温超伝導 / 強相関電子系 |
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| Outline of Final Research Achievements |
There are two remaining issues in cuprate superconductivity: (i) the possibility of non-doped superconducting transition in T'-type cuprates, and (ii) the origin of the pseudogap state observed in the low carrier density region of T-type ones. For (i), we have investigated the possibility of a superconducting transition within the fluctuation exchange approximation using a two-band effective model that explicitly incorporates the oxygen 2p orbital degrees of freedom in the CuO2 plane, and found that the superconducting transition is possible as reported in experiments. As for (ii), it was found that the experimental findings such as the Fermi arc and charge density wave states can be described satisfactorily by considering the staggered flux state in the realistic band structure.
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| Academic Significance and Societal Importance of the Research Achievements |
銅酸化物超伝導体は，通常の金属超伝導体と比較して高い転移温度を持つため，幅広い分野における実用化が強く期待される材料である．しかし，銅酸化物超伝導体のうち試料の制御が比較的容易な物質群は転移温度が約100K以下と比較的低く，実用化のためには，あと5-10K程度の転移温度向上が必要と言われている．本研究において技ギャップ状態の起源を理論的に解析したところ，擬ギャップ状態は超伝導を抑制する働きを持ちうることが判明した．これにより，擬ギャップ状態を選択的に抑制する手段を探索することで転移温度向上を目指すという，性能向上指針を提出することができた．
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