Circularly polarized light irradiated ferromagnetic MnBi$_2$Te$_4$: the long-sought ideal Weyl semimetal

TL;DR

This study demonstrates that circularly polarized light can induce a topological transition in ferromagnetic MnBi$_2$Te$_4$, transforming it into a Weyl semimetal with tunable properties, offering a platform for exploring novel quantum phenomena.

Contribution

First-principles calculations reveal light-induced topological phase transition in MnBi$_2$Te$_4$, enabling control over Weyl points and Fermi arc characteristics in a ferromagnetic material.

Findings

MnBi$_2$Te$_4$ becomes a Weyl semimetal under circularly polarized light.

The Weyl point type evolves from Type-II to Type-I with increasing light intensity.

Fermi arc length can be manipulated by changing light intensity.

Abstract

The interaction between light and non-trivial energy band topology allows for the precise manipulation of topological quantum states, which has attracted intensive interest in condensed matter physics. In this work, using first-principles calculations, we studied the topological transition of ferromagnetic (FM) MnBi$_2$Te$_4$ upon irradiation with circularly polarized light (CPL). We revealed that the MnBi$_2$Te$_4$ can be driven from an FM insulator to a Weyl semimetal with a minimum number of Weyl points, i.e., two Weyl points in systems without time-reversal symmetry. More importantly, in FM MnBi$_2$Te$_4$ with out-of-plane easy magnetization axis, we found that the band dispersion of the WP evolves from Type-II to Type-III and finally to Type-I when the light intensity increases. Moreover, we show that the profile of the characteristic Fermi arc of Weyl semimetal phase is sensitive to changes in light intensity, which enables efficient manipulation of the Fermi arc length of FM MnBi$_2$Te$_4$ in experiments. In addition, for FM MnBi$_2$Te$_4$ with in-plane easy magnetization axis, the system becomes a type I Weyl semimetal under CPL irradiation. With controllable band dispersion, length of Fermi arc, and minimum number of WPs, our results indicate that CPL-irradiated FM MnBi$_2$Te$_4$ is an ideal platform to study novel transport phenomena in Weyl semimetals with distinct band dispersion.