Chiral Hinge Transport in Disordered Non-Hermitian Second-Order Topological Insulators

TL;DR

This paper investigates how chiral hinge transport behaves in disordered non-Hermitian second-order topological insulators, revealing deviations from Hermitian cases and highlighting the role of incoherent scattering.

Contribution

It demonstrates the robustness and fluctuation behavior of hinge states in disordered non-Hermitian 3DSOTIs, extending understanding beyond Hermitian topological insulators.

Findings

Transmission coefficients can differ from the number of hinge channels in non-Hermitian systems.

Fluctuations in transmission are always non-zero due to incoherent scattering.

Hinge state behavior in non-Hermitian systems applies to various topological materials.

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 chiral hinge states, while the fluctuations of transmission coefficients are always non-zero. 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.