Variational Monte Carlo study using new algorithm of excited states in Mott regime

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05428
• 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: Tohoku University
• Principal Investigator: Yokoyama Hisatoshi 東北大学, 理学研究科, 助教 (60212304)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 強相関電子系 / モット転移 / ハバード模型 / 変分モンテカルロ法 / 反強磁性状態 / 超伝導状態 / 光励起 / 冷却原子

Outline of Final Research Achievements

We consider a strongly correlated system in which an energy gap exist between the insulating ground state and excited states. By applying a variational Monte Carlo method, which is often used for ground states, to excited states, we studied how the excited state behaves as a quasi-stationary state after some weak relaxation processes. We found that the pair-formed and paramagnetic states exhibit phase transitions to (super)conducting states with weak excitation strengths, whereas the antiferromagnetic (AF) state preserves an insulating state. The energy is lowest for the AF state. Therefore, after relaxation from an initial transient conductive state, the state becomes an AF state, which is similar to the ground state.

Free Research Field

物性理論

Academic Significance and Societal Importance of the Research Achievements

強い電子相関がある絶縁体の励起後の緩和過程に対応する理論的研究として、動的研究より基礎的な点を明らかにすることで、光励起や光学格子の実験結果を深く追求できる素地ができたと考えられる。通常、励起後の緩和した状態が金属的になるのが当然と考えられているが、モット領域であれば、それが誤解であることを示せた。励起に関しても、半導体の物理のモットの物理が著しく異なることを示せた。主流である動的研究に、本研究の成果は反映される必要があろう。