Influence of magnetic ordering on the optical response of the antiferromagnetic topological insulator MnBi$_2$Te$_4$

TL;DR

This study investigates how magnetic ordering influences the optical properties of the antiferromagnetic topological insulator MnBi₂Te₄, revealing anomalies at the magnetic transition that link electronic structure and magnetism.

Contribution

It provides the first temperature-dependent infrared spectroscopy analysis of MnBi₂Te₄, showing the correlation between magnetic phase transition and optical conductivity changes.

Findings

Optical parameters show anomalies at the magnetic transition temperature.

The electronic band structure is affected by magnetic ordering.

Magnetism influences the bulk electronic properties of MnBi₂Te₄.

Abstract

The layered topological insulator MnBi$_2$Te$_4$ has attracted great interest recently due to its intrinsic antiferromagnetic order, potentially hosting various topological phases. By temperature-dependent infrared spectroscopy over a broad frequency range, we studied the changes in the optical conductivity of MnBi$_2$Te$_4$ at the magnetic ordering temperature. The temperature dependence of several optical parameters reveals an anomaly at the magnetic phase transition, which suggests the correlation between the bulk electronic band structure and the magnetism. We relate our findings to recent reports on the temperature dependence of the electronic band structure of MnBi$_2$Te$_4$.