| Project/Area Number |
25610096
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Condensed matter physics II
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2013-04-01 – 2015-03-31
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| Project Status |
Completed (Fiscal Year 2014)
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| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2014: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2013: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | 量子臨界現象 / 超伝導特性 / 準粒子励起 / 臨界磁場 / 反強磁性 / 渦糸物理 / 有効質量 / 磁場侵入長 / 低温物性測定 / 比熱 / 超伝導 / 上部臨界磁場 / ギャップ構造 / 鉄系超伝導 / 異方的超伝導 / 下部臨界磁場 / 量子ゆらぎ / 量子臨界点 |
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| Outline of Final Research Achievements |
In the vicinity of a quantum critical point, which marks a phase transition at zero temperature, physical properties exhibit deviations from the standard Fermi-liquid theory of metals, and sometimes unconventional superconductivity emerges. An important issue is to clarify the relationship between this superconductivity and the quantum critical fluctuations. In this project, we studied quasiparticle excitations in the superconducting state near a quantum critical point in iron-based superconducting materials. We found that the effective electron mass estimated from the jump in the specific heat at the superconducting transition gives a quantitative agreement with the zero-temperature penetration depth results, showing a divergent increase towards the quantum critical point. Moreover, the vortex core energy also shows an anomalous increase. These results evidence that the quantum criticality affects strongly the electronic state deep inside the superconducting phase.
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