Edge state contributions to high-order harmonic generation in topological condensed matter

In topological insulators the edge states connect the well separated valence and conduction band in momentum space and allow an electronic current flow along the edges of a finite system. As shown in studies before, these edge states can have a significant impact on the generation of harmonic spectra. In this work we simulated the harmonic spectra of two graphene-like flakes with different edge configurations. The harmonic spectra are compared to the spectrum of the bulk where edge states are absent. However, for the non-trivial topological phase of the finite flakes edge states occur. The edge states in momentum space can be manipulated by the edge configuration of the flakes. We investigate how the different electron dynamics with and without edges are reflected in the harmonic spectra for finite flakes and bulk, respectively.