Insulating Half-Heusler TmPdSb with Unusual Band Order and Metallic Surface States

TL;DR

This study combines theoretical and experimental approaches to investigate TmPdSb, a half-Heusler compound with unusual band inversion and metallic surface states, revealing its potential as a topological insulator with unique surface conduction properties.

Contribution

The paper reports the discovery of a half-Heusler TmPdSb with gapped bulk bands and metallic surface states, expanding understanding of topological features in rare-earth half-Heusler compounds.

Findings

Bulk insulating behavior confirmed by transport measurements.

Presence of metallic surface states evidenced by magnetoresistance and weak-antilocalization.

Unusual band inversion in the conductance band observed.

Abstract

We present theoretical and experimental results exploring a half-Heusler compound TmPdSb with unusual band order and metallic surface states. Typically, the half-Heusler systems exhibit topological features in a semimetallic state, and trivial ones in an insulating state. Topological properties of the most of half-Heusler systems are related to the band inversion around the Fermi level, similar to this observed in CdTe/HgTe systems. In the case of TmPdSb we observed the gapped electronic band structure with ``band inversion'' in the conductance band, while the slab-like system realized metallic surface states. The bulk insulating nature of the compound was corroborated by means of electrical transport measurements. The experimental data revealed several features due to the presence of metallic surface states, such as linear magnetoresistance and weak-antilocalization effect, characterized by enhanced coherence length and a very large number of surface conductive channels. Our findings reveal new features of the rare-earth half-Heusler.