Tunable electronic band structure and magnetic anisotropy in two-dimensional Dirac half-metal MnBr3 by external stimulus: strain, magnetization direction, and interlayer coupling

Abstract

Advancing technology and growing interdisciplinary fields create the need for new materials that simultaneously possess several significant physics qualities to meet human demands. Dirac half-metals with massless fermions hold great promise in spintronic devices and optoelectronic devices associated with nontrivial band topologies. In this work, we predict that a MnBr₃ monolayer will be an intrinsic Dirac half-metal based on first-principles calculations. The lattice dynamics and thermodynamic stabilities were demonstrated by calculating the phonon spectra and performing molecular dynamics simulations. One property of a MnBr₃ monolayer is that facile magnetization of its in-plane can be accomplished. A change in the magnetization direction significantly modifies the electronic band structure. When considering the spin–orbit coupling effect, the Dirac cone around the Fermi level in the spin-up channel opens a gap of 35 meV, which becomes a topological nontrivial insulator with a Chern number of −1. The Chern number sign and the chiral edge current can be tuned by changing the magnetization direction. The electronic band structure and magnetic anisotropy energy can be further modulated by applying biaxial and uniaxial strain, as well as introducing interlayer coupling in the bilayer. The unique performance of MnBr₃ will broaden the utilization of two-dimensional magnetism in widespread application.