Classification of Chern Numbers Based on High-Symmetry Points

TL;DR

This paper reveals that in inversion-symmetric Chern insulators, topological phases can be distinguished by skyrmions at high-symmetry points, beyond the Chern number, affecting edge states and transport properties.

Contribution

It introduces a new classification method based on skyrmions at high-symmetry points, expanding the understanding of topological phases in Chern insulators.

Findings

Skyrmions differentiate topological phases at high-symmetry points.

Interfaces exhibit gapless helical states with quantized transport.

Topological transitions can occur without changing the Chern number.

Abstract

The Chern number is a crucial topological invariant for distinguishing the phases of Chern insulators. Here we find that for Chern insulators with inversion symmetry, the Chern number alone is insufficient to fully characterize their topology. Specifically, distinct topological phases can be differentiated based on skyrmions at different high-symmetry points. Interfaces between these topological phases exhibit gapless helical states, which provide counter-propagating transport channels and robust quantized transport. Additionally, we identify topological transitions that do not involve changes in the Chern number but can be characterized by transitions of skyrmions between high-symmetry points. These transitions arise due to the toroidal structure of the two-dimensional Brillouin zone, which is generally applicable to two-dimensional periodic lattice system. Our research introduces new degrees of freedom for controlling topological optical transport and deepens the understanding of Chern insulators with inversion symmetry.