Interplay of Kekul\'e distortions and laser fields in graphene

Abstract

We study the interplay between a Kekul\'e patterned distortion in monolayer graphene and a monochromatic laser irradiation, focusing in the long wavelength approximation of its Landau level structure. Exploiting the symmetries of the system, we calculate in the static regime an exact analytical solution for the energy spectrum and its eigenstates, which in turn allows us to find close expressions for the polarizations in the valley and pseudospin degrees of freedom. We find that due to the valley-momentum coupling, the valley polarization exhibits a distinct magnetic response for the two $K$-valley components. Owing to that, the introduction of the radiation field mixes the Landau levels, and it is shown that by tuning the system to resonance leads to a larger valley-polarization response as compared to the non-resonant scenario.