Cubic binary compounds MnN and MnAs and diluted magnetic Ga1-xMnxN semiconductor alloys: a first-principle study

In this work we report ab initio calculations of the electronic structures of the binary compounds MnN and MnAs, and of the diluted magnetic semiconductor alloys Ga1-xMnxN (x=0.06; 0.03) in the zinc-blende phase. We use the theoretical local density approximation and the generalized gradient approximation within the density functional theory. We follow the evolution of the band structures, density of states and magnetic moments as functions of the lattice parameter of the MnN and MnAs compounds. Depending on the lattice parameter, the binary compounds MnAs and MnN are found to be half-metallic, that is, they exhibit metallic conduction by spin-polarized charge carriers; both materials reach a maximum magnetization of 4.0μB. We also discuss the electronic structures, local magnetic moments, exchange interactions, and the general features of the Ga1-xMnxN alloys. These ferromagnetic alloys are also candidates to be half-metallic materials: the majority-spin states are metallic and the minority-spin states are insulating. The valence band is ferromagnetically coupled to the Mn atoms, and the total magnetization of the cell is 4.0μB, which is independent of the Mn concentration.