Investigation of electronic and magnetic properties in vacancy incorporated monolayer magnesium bromide for spintronics application: an ab-initio study

Abstract

Abstract Alkaline earth-based half-metallic materials attracted spintronics researchers, owing to their outstanding long spin relaxation time and robustness against spin current leakage. Using first principles calculations, defect-induced monolayer magnesium bromide (Mg1−x δ xBr2; x = 0.11, 0.22, 0.33) systems have been studied for the first time. Among these systems, Mg0.89 δ 0.11Br2 showed half-metallic nature that finds application in ultra-fast spintronics. Exfoliation energy (0.12 J/m2) calculation revealed the possibility of exfoliation of the monolayer MgBr2 from its bulk. Phonon dispersion plot confirmed dynamical stability of the free-standing monolayer. The formation energy of Mg vacancy defect (VMg) under Br-rich condition (2 eV) showed, defect-induced favourability. Mg0.89 δ 0.11Br2 has been found to be in a ferromagnetic ground state with a remarkable large spin-up gap (4.84 eV), which limits spin leakage. In addition, significant magnetic anisotropy energy (MAE) per VMg (4.16 meV) has been observed along (100) easy axis direction with a strong ferromagnetic coupling. Electric field modulated electronic structure showed an optimal spin-up gap up to 0.3 V/Å, desirable for the device operation. Robustness of the half-metallicity was confirmed by strain-dependent density of states which is vital during its synthesis and deposition onto a substrate. Hence, from the electronic and magnetic studies, vacancy incorporated monolayer magnesium bromide showed potential applications in spintronics.