Bulk band inversion and surface Dirac cones in LaSb and LaBi : Prediction of a new topological heterostructure

TL;DR

This study uses ab initio calculations to analyze the topological properties of LaSb, LaBi, and their multilayer, revealing band inversion and stable surface Dirac cones indicative of non-trivial topological phases.

Contribution

It provides the first detailed ab initio analysis of LaSb-LaBi multilayers, confirming their topological non-triviality through band inversion and surface state stability.

Findings

Band inversion observed in LaSb-LaBi multilayers.

Stable surface Dirac cones confirmed on (001) surface.

Multilayer exhibits non-trivial topological properties.

Abstract

We perform \textit{ab initio} investigations of the bulk and surface band structures of LaSb and LaBi and resolve the existing disagreements about the topological property of LaSb, considering LaBi as a reference. We examine the bulk band structure for band inversion, along with the stability of surface Dirac cones (if any) to time-reversal-preserving perturbations, as a strong diagnostic test for determining the topological character of LaSb, LaBi and LaSb-LaBi multilayer. A detailed \textit{ab initio} investigation of a multilayer consisting of alternating unit cells of LaSb and LaBi shows the presence of band inversion in the bulk and a massless Dirac cone on the (001) surface, which remains stable under the influence of time-reversal-preserving perturbations, thus confirming the topologically non-trivial nature of the multilayer in which the electronic properties can be tailored as per requirement. A detailed $\mathbb{Z}_2$ invariant calculation is performed to arrive at a holistic conclusion.