Phys. Rev. B 106, 045142 (2022)

Chiral hinge transport in disordered non-Hermitian second-order topological insulators

C. Wang^*, X. R. Wang^†

* Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300350, China

† Physics Department, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong and HKUST Shenzhen Research Institute, Shenzhen 518057, China

* Corresponding author: physcwang@tju.edu.cn

† Corresponding author: phxwan@ust.hk

Abstract

The generalized bulk-boundary correspondence predicts the existence of the chiral hinge states in three-dimensional second-order topological insulators (3DSOTIs), resulting in a quantized Hall effect in three dimensions. Chiral hinge states in Hermitian 3DSOTIs are characterized by the quantized transmission coefficients with zero fluctuations, even in the presence of disorders. Here, we show that chiral hinge transport in disordered non-Hermitian systems deviates from the paradigm of the Hermitian case. Our numerical calculations prove the robustness of hinge states of disordered non-Hermitian 3DSOTIs. The mean transmission coefficients may or may not equal the number of chiral hinge channels, depending on the Hermiticity of the chiral hinge states, while the fluctuations of transmission coefficients are always nonzero. Such fluctuations are not due to the broken chirality of hinge states but the incoherent scatterings of non-Hermitian potentials. The physics revealed here should also be true for one-dimensional chiral channels in topological materials that support chiral boundary states, such as Chern insulators, three-dimensional anomalous Hall insulators, and Weyl semimetals.