Localization trajectory and Chern-Simons axion coupling for bilayer quantum anomalous Hall systems

Article

关键词: PHASE-TRANSITION;    REALIZATION;    CONDUCTANCE;    STATE;   

DOI  :  10.1103/PhysRevB.99.125414

来源: SCIE

【 摘 要 】

Quantum anomalous Hall (QAH) multilayers provide a platform for topological materials with high Chern numbers. We investigate the localization routes of bilayer QAH systems with Chern number C = 2 during the process of increasing disorder, by numerical simulations on their quantum transport properties and the Chern-Simons axion coupling. The localization trajectories present richer behaviors than those in the monolayer with C = 2. For example, there exists a stable intermediate state with C = 1 before localization, which was always unstable in a monolayer. In some cases, this C = 1 state is weak in the sense that its Hall plateau is hardly visible in a mesoscopic sample, but is still stable in the sense of renormalization group. The underlying physics is discussed. During the localization process, the Chern-Simons axion coupling shows a surprising peak which is even more remarkable in the large size limit. The physical origin of this peak is understood by a real-space analysis of the electronic states. As a result, the disordered QAH multilayers can be good candidates for this nontrivial magnetoelectric coupling mediated by orbital motions.

【 授权许可】

Free