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.