Nontrivial topological phase with a zero Chern number

Abstract

A two-dimensional (2D) topological band is characterized by the (first) Chern number. The zero and nonzero Chern numbers usually represent the trivial and nontrivial band topologies, respectively. In this paper, we study an extended Qi-Wu-Zhang model that hosts the topological band with a zero Chern number. We show that the zero Chern number band is topologically nontrivial, characterized by the half-integer wave polarization. The nontrivial topology is manifested by the anisotropic in-gap edge states, which are verified to be robust against 2D particle-hole symmetric disorders.