Zhou Humian, Li Hailong, Xu Dong-Hui, Chen Chui-Zhen, Sun Qing-Feng, Xie X C
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Department of Physics, and Chongqing Key Laboratory for Strongly Coupled Physics, Chongqing University, Chongqing 400044, China.
Phys Rev Lett. 2022 Aug 26;129(9):096601. doi: 10.1103/PhysRevLett.129.096601.
Recently, a half-quantized Hall conductance (HQHC) plateau was experimentally observed in a semimagnetic topological insulator heterostructure. However, the heterostructure was metallic with a nonzero longitudinal conductance, which contradicts the common belief that quantized Hall conductance is usually observed in insulators. In this work, we systematically study the surface transport of a semimagnetic topological insulator with both gapped and gapless Dirac surfaces in the presence of dephasing process. In particular, we reveal that the HQHC is directly related to the half-quantized chiral current along the edge of a strongly dephasing metal. The Hall conductance keeps a half-quantized value for large dephasing strengths, while the longitudinal conductance varies with Fermi energies and dephasing strengths. Furthermore, we evaluate both the conductance and resistance as a function of the temperature, which is consistent with the experimental results. Our results not only provide the microscopic transport mechanism of the HQHC, but also are instructive for the probe of the HQHC in future experiments.
最近，在半磁拓扑绝缘体异质结构中通过实验观测到了半量子化霍尔电导（HQHC）平台。然而，该异质结构是金属性的，具有非零纵向电导，这与通常认为量子化霍尔电导通常在绝缘体中观测到的观点相矛盾。在这项工作中，我们系统地研究了在存在退相干过程的情况下，具有带隙和无带隙狄拉克表面的半磁拓扑绝缘体的表面输运。特别地，我们揭示了HQHC与沿着强退相干金属边缘的半量子化手征电流直接相关。对于大的退相干强度，霍尔电导保持半量子化值，而纵向电导随费米能和退相干强度而变化。此外，我们评估了电导和电阻随温度的变化，这与实验结果一致。我们的结果不仅提供了HQHC的微观输运机制，而且对未来实验中HQHC的探测具有指导意义。
