Confined vs. extended Dirac surface states in topological crystalline insulator nanowires

TL;DR

This paper demonstrates how topological crystalline insulator nanowires can confine Dirac surface states, revealing distinct flux-dependent oscillations and highlighting their potential for manipulating Dirac fermions.

Contribution

It shows that Dirac fermion confinement is achievable in TCI nanowires and explores how different facet terminations affect their electronic properties.

Findings

<100> facet nanowires show Aharonov-Bohm oscillations.

<110> facet nanowires exhibit suppressed oscillations.

TCI nanowires can manipulate Dirac surface states effectively.

Abstract

Confining two dimensional Dirac fermions on the surface of topological insulators has remained an outstanding conceptual challenge. Here we show that Dirac fermion confinement is achievable in topological crystalline insulators (TCI), which host multiple surface Dirac cones depending on the surface termination and the symmetries it preserves. This confinement is most dramatically reflected in the flux dependence of these Dirac states in the nanowire geometry, where different facets connect to form a closed surface. Using SnTe as a case study, we show how wires with all four facets of the <100> type display novel Aharonov-Bohm oscillations, while nanowires with the four facets of the <110> type such oscillations are absent due to a strong confinement of the Dirac states to each facet separately. Our results place TCI nanowires as versatile platform for confining and manipulating Dirac surface states.