Bloch-Zener Oscillations in Graphene and Topological Insulators

TL;DR

This paper demonstrates that superlattices based on zero-gap semiconductors like graphene exhibit unique Bloch-Zener oscillations resulting from the interplay of Bloch oscillations and Zener tunneling, leading to observable current oscillations.

Contribution

It introduces the concept of Bloch-Zener oscillations in graphene and topological insulator superlattices and explains their origin through wave packet dynamics and a two-band model.

Findings

Bloch-Zener oscillations occur in graphene and mercury telluride superlattices.

These oscillations cause distinctive current oscillations in I-V characteristics.

The phenomenon is supported by numerical transport calculations.

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.