Floquet engineering of topological semimetals with bicircularly polarized light

TL;DR

This paper explores how bicircularly polarized light can be used to manipulate the electronic band structures of topological semimetals, revealing tunable phases and potential for controlling topological properties.

Contribution

It demonstrates, through models and simulations, that BCL can induce diverse and tunable topological phases in multifold fermions and line-node semimetals, including gapless and gapped states.

Findings

BCL can preserve or shift band touching points depending on parameters.

Tuning BCL parameters induces transitions between different topological phases.

BCL serves as a versatile tool for engineering topological properties.

Abstract

We study the effect of illumination of bicircularly polarized light (BCL) on topological semimetals, namely multifold fermion and line-node semimetals. We demonstrate, by means of both low-energy and lattice models, that the band-structures of both multifold fermions and line-node semimetal exhibit rich features with BCL illumination. For multifold fermions, we show that if the relative amplitude, $r$, between the two frequency components of the BCL is related to the relative frequency, $\eta$, in such a way that $r^2 = \eta$, then the band touching points remain unchanged without any shift or band gap opening for any choice of the material-dependent parameters. For other choices of the BCL parameters, we find both gapped phases as well as gapless phases with shifted band touching points. Line-node semimetals also exhibit diverse phases, ranging from protected line-nodes under illumination to point nodes, by tuning the BCL parameters $r$ and $\eta$. Overall, our analytical and numerical results establish BCL as a versatile tool for obtaining tunable topological phases.