Observation of a topologically non-trivial surface state in half-Heusler PtLuSb (001) thin films

TL;DR

This paper reports the experimental observation of a topologically non-trivial surface state in PtLuSb thin films, confirming theoretical predictions and highlighting the potential of half-Heusler compounds for spintronic applications.

Contribution

The study provides the first experimental evidence of topological surface states in half-Heusler PtLuSb thin films, combining ARPES measurements with theoretical calculations.

Findings

Identification of a surface state with linear dispersion

Observation of helical spin texture in the surface state

Confirmation of topological insulator behavior in PtLuSb

Abstract

The discovery of topological insulators (TIs), materials with bulk band gaps and protected cross-gap surface states, in compounds such as Bi2Se3 has generated much interest in identifying topological surface states (TSSs) in other classes of materials. In particular, recent theory calculations suggest that TSSs may be found in half-Heusler ternary compounds. If experimentally realizable, this would provide a materials platform for entirely new heterostructure spintronic devices that make use of the structurally-identical but electronically-varied nature of Heusler compounds. Here, we show the presence of a TSS in epitaxially grown thin films of the half-Heusler compound PtLuSb. Spin and angle-resolved photoemission spectroscopy (ARPES), complemented by theoretical calculations, reveals a surface state with linear dispersion and a helical tangential spin texture consistent with previous predictions. This experimental verification of TI behavior is a significant step forward in establishing half-Heusler compounds as a viable material system for future spintronics devices.