2018 Fiscal Year Final Research Report
Higgs mode observation of high temperature superconductors by time-resolved angle-resolved photoelectron spectroscopy
Project/Area Number |
16K13829
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Research Category |
Grant-in-Aid for Challenging Exploratory Research
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Allocation Type | Multi-year Fund |
Research Field |
Condensed matter physics II
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Research Institution | The University of Tokyo |
Principal Investigator |
Kondo Takeshi 東京大学, 物性研究所, 准教授 (40613310)
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Project Period (FY) |
2016-04-01 – 2019-03-31
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Keywords | 光電子分光 / 超伝導 / レーザー |
Outline of Final Research Achievements |
In a copper oxide or iron-based superconductor, depending on the amount of carriers, it can be realized, depending on the amount of carriers, from a pure superconducting state to a characteristic state in which the superconductivity is mixed with a pseudo gap state or charge/spin density wave. These thus provide an intriguing platform to study excitation modes associated with spontaneous symmetry breaking. We studied the dynamics of electron systems by time-resolved ARPES, which can obtain momentum-resolved spectra. We have shown that long-term relaxation components can be observed regardless of superconductivity, and we have found the need to reexamine the notion of "slow relaxation = reconstruction of superconductivity". In addition, we found that the relaxation time changes significantly depending on the intensity of pump power, and explained the discrepancy among the contradicting experimental results.
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Free Research Field |
電子物性
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Academic Significance and Societal Importance of the Research Achievements |
液体窒素温度を超える高い臨界温度を示す超伝導体が約30年前銅酸化物において発見れて以来、銅酸化物高温超伝導体は物性研究の対象として長らく主役を担ってきた。それにも関わらず、高い超伝導臨界温度が生じる機構に関しては未だ統一した見解が得られていない。 超伝導は、伝導を支配する電子が多数の対を組むことで安定化し、背景にある格子振動や不純物による散乱を受けることなく電流を流す特異な電子状態である。超伝導の発現機構を解明する上で、電子同士を対として結びつける”のり”を同定することが重要であり、Bi2212の時間分解ARPES研究で見出した電子系ダイナミクスの理解により応用研究への波及が期待される。
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