Prediction of topological phases in metastable ferromagnetic MPX$_3$ monolayers

TL;DR

This study uses density functional theory to explore the electronic and topological properties of metastable ferromagnetic MPX3 monolayers, revealing potential topological phases influenced by strain and computational methods.

Contribution

It demonstrates the possibility of inducing topological phases in metastable ferromagnetic MPX3 monolayers through strain and discusses the effects of different computational approaches.

Findings

MnPSe3 monolayers show topological semimetal signatures.

Topological phases can be achieved under external biaxial strain.

Hybrid-functional calculations recover topological band structures at 17 GPa.

Abstract

Density functional theory calculations are carried out to study the electronic and topological properties of $M$P$X_3$ ($M$ = Mn, Fe, Co, Ni, and $X$ = S, Se) monolayers in the ferromagnetic (FM) metastable magnetic state. We find that FM MnPSe$_3$ monolayers host topological semimetal signatures that are gapped out when spin-orbit coupling (SOC) is included. These findings are supported by explicit calculations of the Berry curvature and the Chern number. The choice of the Hubbard-$U$ parameter to describe the $d$-electrons is thoroughly discussed, as well as the influence of using a hybrid-functional approach. The presence of band inversions and the associated topological features are found to be formalism-dependent. Nevertheless, routes to achieve the topological phase via the application of external biaxial strain are demonstrated. Within the hybrid-functional picture, topological band structures are recovered under a pressure of 15% (17 GPa). The present work provides a potential avenue for uncovering new topological phases in metastable ferromagnetic phases.