Theory of photoinduced Floquet Weyl semimetal phases

TL;DR

This paper demonstrates how linearly polarized light can induce and control Weyl points in a band insulator using Floquet theory, revealing a rich phase diagram and tunable anomalous Hall conductivity.

Contribution

It introduces a theoretical framework for photoinducing Weyl points in insulators and classifies different types, expanding understanding of light-controlled topological phases.

Findings

Photoinduced Weyl points depend on light frequency and polarization.

The phase diagram includes various topological phases characterized by Chern numbers.

Anomalous Hall conductivity shows nonmonotonous behavior due to Weyl point shifts.

Abstract

The Weyl semimetal exhibits various interesting physical phenomena because of the Weyl points, i.e., linear band-crossings. We show by Floquet theory that a linearly polarized light applied to a band insulator can induce controllable Weyl points. In a tight-binding model, we classify different types of photoinduced Weyl points that lead to a rich phase diagram characterized by the Chern number defined on each momentum slices of the bulk states. Taking account of the nonequilibrium electron distribution, we calculate and explain the nonmonotonous anomalous Hall conductivity in terms of the light frequency controlled shift of Weyl points' position, which also allows us to examine the conductivity's dependence on the driving electric field.