Floquet spectrum and driven conductance in Dirac materials: Effects of Landau-Zener-St\"uckelberg-Majorana interferometry

TL;DR

This paper uses a semiclassical approach to analyze the Floquet spectrum and driven conductance in Dirac materials like graphene and Weyl semimetals under strong AC fields, revealing oscillatory behaviors due to quantum interference effects.

Contribution

It provides the first rigorous quantitative analysis of driven linear conductance in graphene and Weyl semimetals, highlighting the roles of Ramsauer-Townsend and LZSM interference effects.

Findings

Oscillatory conductance as a function of radiation intensity.

Identification of Ramsauer-Townsend and LZSM interference contributions.

Quantitative agreement with theoretical predictions of quantum interference effects.

Abstract

Using the Landau-Zener-St\"uckelberg-Majorana-type (LZSM) semiclassical approach, we study both graphene and a thin film of a Weyl semimetal subjected to a strong AC electromagnetic field. The spectrum of quasi energies in the Weyl semimetal turns out to be similar to that of a graphene sheet. Earlier it has been predicted qualitatively that the transport properties of strongly-irradiated graphene oscillate as a function of the radiation intensity [S.V. Syzranov et al., Phys. Rev. B 88, 241112 (2013)]. Here we obtain rigorous quantitative results for a driven linear conductance of graphene and a thin film of a Weyl semimetal. The exact quantitative structure of oscillations exhibits two contributions. The first one is a manifestation of the Ramsauer-Townsend effect, while the second contribution is a consequence of the LZSM interference defining the spectrum of quasienergies.