High-Chern number phase in the topological insulator multilayer structures

TL;DR

This paper develops a method to determine Chern numbers in topological insulator multilayers, revealing how magnetic doping and layer thickness influence high-Chern number phases, with implications for experimental realization.

Contribution

It introduces an effective approach to calculate Chern numbers and systematically studies phase diagrams, highlighting mechanisms for high-Chern number phases in multilayer structures.

Findings

High-Chern phases are linked to band inversion mechanisms.

Multiple band degeneracies can lead to Chern number changes greater than one.

High-Chern phases can be realized in various multilayer configurations.

Abstract

The high-Chern number phases with a Chern number C>1 have been observed in a recent experiment that performed on the topological insulator (TI) multilayer structures, consisting of the alternating magnetic-doped and undoped TI layers. In this paper, we develop an effective method to determine the Chern numbers in the TI multilayer structures and then make a systematic study on the Chern number phase diagrams that are modulated by the magnetic doping and the middle layer thickness. We point out that in the multilayer structure, the high-C behavior can be attributed to the band inversion mechanisms. Moreover, we find that the lowest bands may be multifold degenerate around the Gamma point, and when they are inverted, the Chern number change will be larger than one. Besides the TI multilayer structures implemented in the experiment, we also explore the high-C phase realizations in two other kinds of the TI multilayer structures. The implications of our results for experiments are discussed.