Floquet engineering of multifold fermions

Abstract

Using Floquet theory, we investigate the effect of light on triplefold fermions. We study a low-energy model as well as a simplified tight-binding model under illumination. We find that the threefold degeneracy remains symmetry protected even after applying light if the original band structure is rotationally symmetric around the degeneracy. Otherwise, light can lift the degeneracy and open up a gap. We further investigate the effect of light on the topological Fermi arcs by means of numerical computations. The changes caused by illumination are reflected in experimentally detectable signatures, such as the anomalous Hall conductivity, which we calculate.