$(111)$ surface states of SnTe

TL;DR

This paper demonstrates that passivating the pristine (111) surface of SnTe reveals topological surface states, enabling external control of Dirac node energies, which is crucial for multi-valley transport applications.

Contribution

It shows that chemisorption passivation uncovers topological surface states on SnTe (111) surfaces and allows external tuning of Dirac node energies.

Findings

Passivation reveals topological surface states obscured in pristine SnTe.

Extracted anisotropic Fermi velocities, penetration lengths, and spin textures.

Chemisorption enables external control of Dirac node energies.

Abstract

The characterization and applications of topological insulators depend critically on their protected surface states, which, however, can be obscured by the presence of trivial dangling bond states. Our first principle calculations show that this is the case for the pristine $(111)$ surface of SnTe. Yet, the predicted surface states unfold when the dangling bond states are passivated in proper chemisorption. We further extract the anisotropic Fermi velocities, penetration lengths and anisotropic spin textures of the unfolded $\bar\Gamma$- and $\bar M$-surface states, which are consistent with the theory in http://dx.doi.org/10.1103/PhysRevB.86.081303 Phys. Rev. B 86, 081303 (R). More importantly, this chemisorption scheme provides an external control of the relative energies of different Dirac nodes, which is particularly desirable in multi-valley transport.