Floquet Engineering of Multifold Fermions

TL;DR

This paper explores how light influences triple fold fermions using Floquet theory, revealing conditions under which degeneracies are preserved or lifted, and examining effects on topological features and measurable conductivities.

Contribution

It introduces a detailed analysis of light effects on multifold fermions, highlighting symmetry conditions for degeneracy preservation and the impact on topological properties.

Findings

Degeneracy remains under rotational symmetry with light

Light can lift degeneracy if symmetry is broken

Illumination affects topological Fermi arcs and Hall conductivity

Abstract

Using Floquet theory, we investigate the effect of light on triple fold fermions. We study a low energy model as well as a simplified tight binding model under illumination. We find that the three fold 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.