| Project/Area Number |
16K17752
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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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 | Chiba Institute of Technology |
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Principal Investigator |
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| Research Collaborator |
NASU Joji
MIYATA Takafumi
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2016: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
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| Keywords | 励起子絶縁体 / 変分モンテカルロ法 / ２軌道ハバード模型 / 励起子秩序 / 物性理論 |
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| Outline of Final Research Achievements |
To study the possibility of an excitonic insulator which application is expected as a novel optical device, we investigated the stability using a variational Monte Carlo calculation. As a lattice model for the excitonic state, we adopted a general two-orbital Hubbard model, in which the strength of electron correlation and potential between orbitals on a site can be changed depending on the materials. Although the appearance of the excitonic insulator is not determinately observed, our calculation results indicated that such an excitonic order is universally stabilized in a wide range of parameters. Thus, the excitonic insulator should be detected in many materials, and its application should be also achieved with sufficient possibility.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究で調査した励起子絶縁体は，従来の半導体に代わる新奇スイッチング電子デバイスとしての応用化が期待されている。励起子絶縁体の存在については５０年以上前から理論的に認識されてきたが，私たちの研究は変分モンテカルロ法という非摂動計算を用いることで，より現実の物質に近い格子模型で励起子絶縁体の実現性を明らかにした。この手法は現代の高速計算機を利用しており，５０年以上前にはできなかった高精度の計算手法である。実際に，本研究結果は励起子絶縁体に相当する秩序状態が，これまで計算が困難であった強相関系で十分な安定性を持つことを示しており，今後実験的に多くの物質で発見される可能性が高いことを示唆している。
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