Kerr, Faraday, and magnetoelectric effects in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>MnBi</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math> thin films

Abstract

The topological magnetoelectric effect (TME) is a characteristic property of topological insulators. In this paper, we use a simplified coupled-Dirac-cone electronic structure model to theoretically evaluate the THz and far infrared Kerr and Faraday responses of thin films of ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ with up to $N=10$ septuple layers with the goal of clarifying the relationship between these convenient magnetooptical observables and the TME. We find that for even $N$, the linear Kerr and Faraday responses to an electric field vanish in the low-frequency limit, even though the magnetoelectric response is large and approximately quantized.

Topics & Concepts