2014/06/30 by Gonzalo Usaj, P. M. Perez-Piskunow, L. E. F. Foa Torres +1 · 2 citations
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.90.115423
published as Phys. Rev. B 90, 115423 (2014) · 12 pages, 8 figures. Revised version, submitted to PRB
arxiv created 2014/09/01 · arxiv updated 2014/09/23
In the presence of a circularly polarized mid-infrared radiation graphene develops dynamical band gaps in its quasi-energy band structure and becomes a Floquet insulator. Here we analyze how topologically protected edge states arise inside these gaps in the presence of an edge. Our results show that the gap appearing at ℏΩ/2, where ℏ Ω is the photon energy, is bridged by two chiral edge states whose propagation direction is set by the direction of the polarization of the radiation field. Therefore, both the propagation direction and the energy window where the states appear can be controlled externally. We present both analytical and numerical calculations that fully characterize these states. This is complemented by simple topological arguments that account for them and by numerical calculations for the case of semi-infinite sample, thereby eliminating finite size effects.