Two-dimensional ferromagnetic semiconductor VBr3 with tunable anisotropy

TL;DR

This study investigates the electronic and magnetic properties of VBr3 in bulk and monolayer forms, revealing strain-tunable magnetic anisotropy and Curie temperature enhancements, highlighting its potential for spintronic applications.

Contribution

The paper demonstrates that tensile strain can significantly alter the magnetic anisotropy and increase the Curie temperature of VBr3 monolayers, a novel approach for tuning 2D ferromagnetic semiconductors.

Findings

VBr3 bulk has a small orbital moment and weak in-plane anisotropy.

Strain induces a transition to out-of-plane anisotropy and increases T_C.

Curie temperature can be raised from 20 K to over 100 K under strain.

Abstract

Two-dimensional (2D) ferromagnets (FMs) have attracted widespread attention due to their prospects in spintronic applications. Here we explore the electronic structure and magnetic properties of the bulk and monolayer of VBr$_{3}$ in the honeycomb lattice, using first-principles calculations, crystal field level analyses, and Monte Carlo simulations. Our results show that VBr$_{3}$ bulk has the $e'_{g}$$^2$ ($S$=1) ground state and possesses a small orbital moment and weak in-plane magnetic anisotropy. Those results well explain the recent experiments. More interestingly, we find that a tensile strain on the semiconducting VBr$_{3}$ monolayer tunes the ground state into $a_{1g}$$^1$$e'_{g}$$^1$ and thus produces a large orbital moment and a strong out-of-plane anisotropy. Then, the significantly enhanced FM superexchange and single ion anisotropy (SIA) would raise $T_{\rm C}$ from 20 K for the bare VBr$_{3}$ monolayer to 100-115 K under a 2.5$\%$-5$\%$ strain. Therefore, VBr$_{3}$ would be a promising 2D FM semiconductor with a tunable anisotropy.