Suppression of the Spectral Weight of Topological Surface States on the Nanoscale via Local Symmetry Breaking

TL;DR

This paper demonstrates that local symmetry breaking on the nanoscale can significantly suppress the spectral weight of topological surface states in SnTe, offering a new way to manipulate topological properties for device applications.

Contribution

It shows that local symmetry breaking can suppress topological surface states over large energy ranges, a novel approach compared to global perturbations.

Findings

Local symmetry breaking suppresses surface state tunneling.

Suppression spans energy ranges up to the bulk band gap.

Ab initio calculations confirm reduced spectral weight.

Abstract

In topological crystalline insulators the topological conducting surface states are protected by crystal symmetry, in principle making it possible to pattern nanoscale insulating and conductive motifs solely by breaking local symmetries on an otherwise homogenous, single-phase material. We show using scanning tunneling microscopy/spectroscopy that defects that break local symmetry of SnTe suppress electron tunneling over an energy range as large as the bulk band gap, an order of magnitude larger than that produced globally via magnetic fields or uniform structural perturbations. Complementary ab initio calculations show how local symmetry breaking obstructs topological surface states as shown by a threefold reduction of the spectral weight of the topological surface states. The finding highlights the potential benefits of manipulating the surface morphology to create devices that take advantage of the unique properties of topological surface states and can operate at practical temperatures.