A first-principles investigation of band inversion in topologically nontrivial Na2AgX (X= As, Sb and Bi) full Heusler compounds

TL;DR

This study uses first-principles calculations to explore the structural stability and topological electronic properties of Na2AgX (X= As, Sb, Bi) full Heusler compounds, revealing their stable, nontrivial topological nature.

Contribution

It provides the first detailed first-principles analysis of the topological properties of Na2AgX Heusler compounds, including the effects of spin-orbit coupling.

Findings

All studied compounds are structurally stable with negative formation energies.

They are topologically non-trivial regardless of spin-orbit coupling effects.

Spin-orbit coupling has minimal impact on their electronic topological properties.

Abstract

Topological nontrivial nature are the latest phases to be discovered in condensed matter physics with insulating bulk band gaps and topologically protected metallic surface states; they are one of the current hot topics because of their unique properties and potential applications. In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the Na${}_{2}$AgX (X= As, Sb and Bi) full Heusler compounds, using the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method. We have originated that the Hg${}_{2}$CuTi structure is appropriate in all studied materials. The negative values of the calculated formation energies mean that these compounds are energetically stable. The band structure is studied for the two cases relating the existence and the absence of spin-orbital couplings, where all materials are shown to be topologically non-trivial compounds. Spin orbital couplings were noticed to have no significant effect on the electronic properties such as the topological order.