Metallic surface electronic state in half-Heusler compounds RPtBi (R = Lu, Dy, Gd)

TL;DR

This study investigates the surface electronic structure of RPtBi compounds using ARPES, revealing spin-orbit splitting and Kramers' degeneracy, but no definitive topological insulator behavior was observed.

Contribution

First detailed ARPES measurements of RPtBi surface states, combining experimental data with calculations to analyze their topological properties.

Findings

Spin-orbit splitting observed in surface bands

Kramers' degeneracy confirmed at high symmetry points

No conclusive evidence of topologically non-trivial states

Abstract

Rare-earth platinum bismuth (RPtBi) has been recently proposed to be a potential topological insulator. In this paper we present measurements of the metallic surface electronic structure in three members of this family, using angle resolved photoemission spectroscopy (ARPES). Our data shows clear spin-orbit splitting of the surface bands and the Kramers' degeneracy of spins at the Gamma and M points, which is nicely reproduced with our full-potential augmented plane wave calculation for a surface electronic state. No direct indication of topologically non-trivial behavior is detected, except for a weak Fermi crossing detected in close vicinity to the Gamma point, making the total number of Fermi crossings odd. In the surface band calculation, however, this crossing is explained by another Kramers' pair where the two splitting bands are very close to each other. The classification of this family of materials as topological insulators remains an open question.