Bulk and surface electron scattering in disordered Bi$_{2}$Te$_{3}$ probed by quasiparticle interference

TL;DR

This study uses scanning tunneling microscopy and spectroscopy to analyze electron scattering in disordered Bi$_{2}$Te$_{3}$, revealing topological surface states, bulk-surface interactions, and the effects of magnetic fields.

Contribution

It provides high-resolution quasiparticle interference data and spin-selective calculations to understand surface and bulk electron scattering in disordered Bi$_{2}$Te$_{3}$.

Findings

Absence of backscattering confirms topological protection.

Identification of bulk-surface scattering modes.

No significant changes under magnetic fields up to 15 T.

Abstract

We investigated the electronic properties of the topological insulator Bi$_{2}$Te$_{3}$ by scanning tunneling microscopy and spectroscopy at low temperature. We obtained high-resolution quasiparticle interference data of the topological surface Dirac electrons at different energies. Spin-selective joint density of states calculations were performed for surface and bulk electronic states to interpret the observed quasiparticle interference data. The topological properties of our crystals are demonstrated by the absence of backscattering along with the linear energy dispersion of the dominant scattering vector. In addition, we detect non-dispersive scattering modes which we associate with bulk-surface scattering and, thus, allow an approximate identification of the bulk energy gap range based on our quasiparticle interference data. Measurements of differential conductance maps in magnetic fields up to 15 T have been carried out, but no strong modifications could be observed.