STM imaging of a bound state along a step on the surface of the topological insulator Bi$_2$Te$_3$

TL;DR

This study uses STM to investigate a one-dimensional bound state along a step edge on Bi2Te3, revealing how topological surface states interact with structural defects and providing a detailed theoretical model.

Contribution

It presents the first detailed STM analysis of a bound state along a step on Bi2Te3 and introduces a theoretical formula explaining its properties.

Findings

Bound state runs parallel to the step edge and is localized at a characteristic distance.

The bound state is observable within the bulk gap region.

Theoretical model fits the experimental data and enhances understanding of topological surface states.

Abstract

Detailed study of the LDOS associated with the surface-state-band near a step-edge of the strong topological-insulator Bi2Te3, reveal a one-dimensional bound state that runs parallel to the stepedge and is bound to it at some characteristic distance. This bound state is clearly observed in the bulk gap region, while it becomes entangled with the oscillations of the warped surface band at high energy, and with the valence band states near the Dirac point. Using the full effective Hamiltonian proposed by Zhang et al., we obtain a closed formula for this bound state that fits the data and provide further insight into the general topological properties of the electronic structure of the surface band near strong structural defects.