MgTa2N3: A new reference Dirac semimetal

TL;DR

This paper predicts MgTa2N3 as a new Dirac semimetal with a Fermi level at the Dirac point, and explores topological phase transitions induced by symmetry breaking, supported by first-principles calculations.

Contribution

It introduces MgTa2N3 as a novel Dirac semimetal and analyzes its topological properties and phase transitions through symmetry analysis and computational methods.

Findings

MgTa2N3 hosts a Dirac semimetal phase with the Fermi level at the Dirac point.

Lattice symmetry breaking can induce topological phase transitions.

The study identifies topologically protected surface states and Fermi arcs.

Abstract

We present a prediction of the Dirac semimetal (DSM) phase in MgTa2N3 based on first-principles calculations and symmetry analysis. In this material, the Fermi level is located exactly at the Dirac point without additional Fermi surface pockets. The band inversion associated with the Dirac cone involves the d orbitals of two structurally inequivalent Ta atoms with octahedral and trigonal prismatic coordination spheres. We further show that the lattice symmetry breaking can realize topological phase transitions from the DSM phase to a triple nodal point semimetal, Weyl semimetal or topological insulator. The topologically protected surface states and the non-protected Fermi arc surface states are also studied.