Ripple modulated electronic structure of a 3D topological insulator

TL;DR

This study demonstrates that one-dimensional ripples on a 3D topological insulator surface can modulate electronic properties, offering a new method to control Dirac electrons locally for potential applications.

Contribution

It reveals how physical buckling or ripples influence the electronic structure of topological insulators, providing a pathway for local electronic property manipulation.

Findings

Buckling induces periodic potential modulation in Bi2Te3.

Surface and bulk states are modulated by topographic ripples.

Ripples can be engineered via strain for device applications.

Abstract

3D topological insulators, similar to the Dirac material graphene, host linearly dispersing states with unique properties and a strong potential for applications. A key, missing element in realizing some of the more exotic states in topological insulators is the ability to manipulate local electronic properties. Analogy with graphene suggests a possible avenue via a topographic route by the formation of superlattice structures such as a moir\'e patterns or ripples, which can induce controlled potential variations. However, while the charge and lattice degrees of freedom are intimately coupled in graphene, it is not clear a priori how a physical buckling or ripples might influence the electronic structure of topological insulators. Here we use Fourier transform scanning tunneling spectroscopy to determine the effects of a one-dimensional periodic buckling on the electronic properties of Bi2Te3. By tracking the spatial variations of the scattering vector of the interference patterns as well as features associated with bulk density of states, we show that the buckling creates a periodic potential modulation, which in turn modulates the surface and the bulk states. The strong correlation between the topographic ripples and electronic structure indicates that while doping alone is insufficient to create predetermined potential landscapes, creating ripples provides a path to controlling the potential seen by the Dirac electrons on a local scale. Such rippled features may be engineered by strain in thin films and may find use in future applications of topological insulators.