Pressure effects on the electronic and magnetic properties of GaxV1−xN compounds: Ab-initio study

We report an ab-initio study of the pressure effects on the electronic and the magnetic properties of GaxV1−xN compounds (x=0.25, 0.50 and 0.75) in wurtzite-derived structures. We use the full-potential linearized augmented plane wave plus local orbitals method (LAPW + lo) within of the spin density functional theory framework. The lattice constant is found to vary linearly with Ga-concentration. The magnetic moment changes for a critical pressure. At x=0.75, a rather abrupt onset of the magnetic moment from 0 to 2 μB at Pcr∼22.8 GPa is observed. For x=0.25 and 0.50 Ga concentrations, the magnetic moment increases gradually when the pressure decreases toward the equilibrium value. We study the transition pressure dependence to a ferromagnetic phase near the onset of magnetic moment for each GaxV1−xN compounds. The calculation of the density of states with Ga concentration is carried out considering two spin polarizations. The results reveal that for x=0.75 the compound behaves as a conductor for the spin-up polarization and that the density of states for spin-down polarization is zero at the Fermi level. At this concentration the compound presents a half metallic behavior; therefore this material could be potentially useful as spin injector. At high pressures P>Pcr the compounds exhibit a metallic behavior.