Bloch-Zener oscillations in graphene and topological insulators

Abstract

We show that superlattices based on zero-gap semiconductors such as graphene and mercury telluride exhibit characteristic Bloch-Zener oscillations that emerge from the coherent superposition of Bloch oscillations and multiple Zener tunneling between the electron and hole branch. We demonstrate this mechanism by means of wave-packet dynamics in various spatially periodically modulated nanoribbons subject to an external bias field. The associated Bloch frequencies exhibit a peculiar periodic bias dependence, which we explain within a two-band model. Supported by extensive numerical transport calculations, we show that this effect gives rise to distinct current oscillations observable in the $I$-$V$ characteristics of graphene and mercury telluride superlattices.