Driven conductance of an irradiated semi-Dirac material

TL;DR

This paper studies how periodic irradiation affects the electronic conductance and edge states of semi-Dirac materials, revealing gap openings, angular dependencies, and unique edge mode behaviors not seen in graphene.

Contribution

It introduces a Floquet scattering matrix approach to analyze inelastic scattering, gap formation, and edge mode dynamics in irradiated semi-Dirac materials, highlighting differences from graphene.

Findings

Irradiation induces angular-dependent band gaps in semi-Dirac materials.

Conductance exhibits dips corresponding to Floquet band gaps.

Edge modes in nanoribbons can decouple from the bulk and penetrate under irradiation.

Abstract

We theoretically investigate the electronic and transport properties of a semi-Dirac material under the influence of an external time dependent periodic driving field (irradiation) by means of Floquet theory. We explore the inelastic scattering mechanism between different side-bands, induced by irradiation, by using Floquet scattering matrix approach. The scattering probabilities between two nearest side-bands depend monotonically on the strength of the amplitude of the irradiation. The external irradiation induces gap into the band dispersion which is strongly dependent on the angular orientation of momentum. Although, the high frequency limit indicates that the gap opening does not occur in an irradiated semi-Dirac material, a careful analysis of the full band structure beyond this limit reveals that gap opening indeed appears for higher values of momentum (away from the Dirac point). Furthermore, the angular dependent dynamical gap is also present which cannot be captured within the high frequency approximation. The contrasting features of irradiated semi-Dirac material, in comparison to irradiated graphene, can be probed via the behavior of conductance. The latter exhibits the appearance of non-zero conductance dips due to the gap opening in Floquet band spectrum. Moreover, by considering a nanoribbon geometry of such material, we also show that it can host a pair of edge modes which are fully decoupled from the bulk, which is in contrast to the case of graphene nanoribbon where the edge modes are coupled to the bulk. We also investigate that if the nanoribbon of this material is exposed to the external irradiation, decoupled edge modes penetrate into the bulk.