Theoretical Investigation of the Electronic Structure and Magnetic Properties in Ferromagnetic Rock-Salt and Zinc Blende Structures of 3d (V)-Doped MgS

Abstract

In this work, we studied the properties of vanadium doped binary MgS compound Mg1−xVxS (x = 0.125, 0.25, 0.50 and 0.75) in both ferromagnetic rock-salt and zinc-blende structures. The studied properties are structural, electronic and magnetic. The objective of this study is to explore the new dilute magnetic semiconductor systems. We have used two approximations to simulate these properties: Wu–Cohen generalized gradient approximation for structural properties, and the modified Becke–Johnson potential combined with the local density approximation for electronic and magnetic properties. The general context in which the calculations are done is based on the formalism of the spin-polarized density functional theory and the full-potential linear-augmented plane wave method. Among the various compounds studied, we have identified a ferromagnetic semiconducting behavior in the rock-salt structure. In the zinc-blende structure, we have one metallic candidate consisting of 75% V-doping of the Mg-sublattice, and all other compounds have a half-metallic ferromagnetic behavior. We conclude that the Mg1−xVxS compounds, for x = 0.125, 0.25 and 0.50, in the zinc-blende structure are a diluted magnetic semi-conductors materials. To see the effects of the exchange splitting process, the exchange constants N0α and N0β are calculated. For each concentration x, we have found the values of the total magnetic moment equal to 3 μβ excepted for the case of Mg0.25 V0.75S compound in the zinc-blende structure. The value of the total magnetic moment is due principally to V magnetic atom and to other both nonmagnetic atoms Mg and S, which show small local magnetic moments localized on their sites. The presence of ferromagnetic order in this type of compound can be explained by the p-d hybridization phenomena.