Robust Half-Metallicity in a Chromium-Substituted AlN

We investigate half metallicity in a chromium (Cr)-substituted AlN dilute magnetic semiconductor using the full-potential linearized augmented plane-wave method. Our results show that Al_0.75Cr_0.25N is half metal and holds a net integer magnetic moment of 3μ_β with lattice compression. The half−metallic nature is maintained from the relaxed lattice constant 4.36 Å to 4.09 Å. An abrupt change of the physical properties is observed at a robust transition lattice constant of 4.09 Å, and the material transforms from half metal to metal. We find that up to 6% compression, the material maintains its half-metallic nature. Furthermore, we also confirm that the origin of ferromagnetism in Al_0.75Cr_0.25N is double exchange.