Study of the mechanism of high-temperature superconductivity based on optimized Monte Carlo method

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K05559
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Yanagisawa Takashi 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 招聘研究員 (90344217)
• Co-Investigator(Kenkyū-buntansha): 長谷 泉 国立研究開発法人産業技術総合研究所, エレクトロニクス・製造領域, 主任研究員 (00357774)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 量子多体問題 / 強相関電子系 / 高温超伝導 / 最適化モンテカルロ法 / ハバードモデル / 反強磁性ゆらぎ / 多体効果 / 強相関超伝導

Outline of Final Research Achievements

We investigated electronic properties of strongly correlated electron systems by using an optimization variational Monte Carlo method. The electron correlation effect plays an important role in strongly correlated systems. We use an improved wave function being a wave function of off-diagonal type. The may-body effect plays an important role as an origin of antiferromagnetism and superconductivity in correlated electron systems. We investigated electronic models such as the two-dimensional Hubbard model and the three-band d-p model. We have obtained the ground-state phase diagram for these model including superconducting and antiferromagnetic phases. The ground-state phase diagram is consistent with that is obtained by experiments for high-temperature cuprates. There is a crossover between weakly correlated region and strongly correlated one as the Coulomb interaction increases. High-temperature superconductivity will be possible in strongly correlated region.

Free Research Field

量子多体問題

Academic Significance and Societal Importance of the Research Achievements

高温超伝導の機構を明らかにすることは、基礎科学において重要であり新たなパラダイムの形成につながる。応用面からも非常に重要であり、高温超伝導機構の解明により、新しい高温超伝導体のデザインが可能となり新超伝導体の発見につながると期待できる。温超伝導体が実現したならば社会的インパクトは非常に大きい。