Half-Heusler Compounds as a New Class of Three-Dimensional Topological Insulators

TL;DR

This study uses first-principles calculations to show that certain half-Heusler compounds can be transformed into three-dimensional topological insulators through strain, revealing new quantum material possibilities.

Contribution

It demonstrates that uniaxial strain can induce topological insulator phases in half-Heusler compounds, a novel approach in this class of materials.

Findings

LaPtBi exhibits band-inversion as a prototype system.

Uniaxial strain opens a bandgap while maintaining inverted bands.

Strained LaPtBi confirmed as a 3D topological insulator via Z2 invariants.

Abstract

Using first-principles calculations within density functional theory, we explore the feasibility of converting ternary half-Heusler compounds into a new class of three-dimensional topological insulators (3DTI). We demonstrate that the electronic structure of unstrained LaPtBi as a prototype system exhibits distinct band-inversion feature. The 3DTI phase is realized by applying a uniaxial strain along the [001] direction, which opens a bandgap while preserving the inverted band order. A definitive proof of the strained LaPtBi as a 3DTI is provided by directly calculating the topological Z2 invariants in systems without inversion symmetry. We discuss the implications of the present study to other half-Heusler compounds as 3DTI, which, together with the magnetic and superconducting properties of these materials, may provide a rich platform for novel quantum phenomena.