Chiral transport and electronic correlations in surface states of HfNiSn single crystals

TL;DR

This study investigates the surface states of HfNiSn single crystals, revealing chiral transport and electronic correlations that suggest a topologically nontrivial state without band inversion, akin to quantum Hall effects.

Contribution

It demonstrates a new mechanism for topological states arising from surface correlations in non-inverted insulators, expanding understanding of topological phenomena.

Findings

Surface transport shows weak anti-localization indicating 2D metallic states.

Nonlinear I(V) curves suggest electronic correlations and chiral, nonlocal transport.

Evidence of topologically nontrivial surface states without band inversion.

Abstract

In most topological insulators, the valence and conduction band appear in reverse or inverted order compared to an equivalent insulator with isolated atoms. Here, we explore a different route towards topologically nontrivial states that may arise from metallic states present on the surface of bulk insulators without such band inversion. High-quality single crystals of HfNiSn show surface transport with weak anti-localization, consistent with a two-dimensional metallic state in the presence of strong spin-orbit coupling. Nonlinear I(V) curves indicate electronic correlations related to a chiral, nonlocal transport component that is qualitatively similar to a quantum Hall edge state, yet in the absence of external magnetic fields. The correlations themselves may play a decisive role in creating an apparent topologically nontrivial state on the HfNiSn surface.