Surface states scattering from a step defect in topological insulator Bi_{2}Te_{3}

TL;DR

This paper theoretically investigates how surface states in topological insulator Bi2Te3 scatter from step defects, revealing energy-dependent transmission, resonant reflection, and Friedel oscillations consistent with experimental observations.

Contribution

It provides a detailed quantum-mechanical analysis of scattering phenomena on Bi2Te3 surfaces, highlighting the effects of warping and particle-hole symmetry on electron transmission and local density of states.

Findings

Perfect transmission along Γ–M direction at high energy.

Finite reflection and resonant total reflection along Γ–K direction.

Friedel oscillations with power-law decay matching STM experiments.

Abstract

We study theoretically by a quantum-mechanical approach the general scattering problem of a straight step defect on the surface of topological insulator $\mathrm{Bi}_{2}\mathrm{Te}_{3}$ with strong warping effect. At high energy where the warping effect is large, an incident electron on a step defect running along $\Gamma-\mathrm{M}$ direction may exhibit perfect transmission whereas on a defect running along $\Gamma-\mathrm{K}$ direction has a finite probability to be reflected and may even exhibit resonant total reflection. Transmission properties in the latter case are also very sensitive to whether there is particle-hole symmetry. The predicted Friedel oscillations and the power-law decaying behavior of the local density of states (LDOS) near the defect are in good agreement with recent scanning tunneling microscope experiments on $\mathrm{Bi}_{2}\mathrm{Te}_{3}$. The high-energy LDOS of the surface states is also found to show the multi-periodic Friedel oscillations, caused by competing characteristic scattering processes.