Kane-Mele-Hubbard model on the pi-flux honeycomb lattice

Article

关键词: TOPOLOGICAL CRYSTALLINE INSULATOR;    PHASE-TRANSITION;    CHERN INSULATOR;    REALIZATION;    STATES;   

DOI  :  10.1103/PhysRevB.90.075140

来源: SCIE

【 摘 要 】

We consider the Kane-Mele-Hubbard model with a magnetic pi flux threading each honeycomb plaquette. The resulting model has remarkably rich physical properties. In each spin sector, the noninteracting band structure is characterized by a total Chern number C = +/- 2. Fine-tuning of the intrinsic spin-orbit coupling lambda leads to a quadratic band crossing point associated with a topological phase transition. At this point, quantum Monte Carlo simulations reveal a magnetically ordered phase that extends to weak coupling. Although the spinful model has two Kramers doublets at each edge and is explicitly shown to be a Z(2) trivial insulator, the helical edge states are protected at the single-particle level by translation symmetry. Drawing on the bosonized low-energy Hamiltonian, we predict a correlation-induced gap as a result of umklapp scattering for half-filled bands. For strong interactions, this prediction is confirmed by quantum Monte Carlo simulations.

【 授权许可】

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