Electronic Structure and Magnetic Properties of Cr-Doped AlN

To understand the electronic and magnetic properties, we have studied Cr-doped zinc-blende AlN system in detail by applying a first-principle plane wave pseudopotential method based on the density functional theory within the local spin density approximation. The analyses of the band structures, density of states, exchange interactions, and magnetic moments show that Al_1-xCr_xN alloys may exhibit a half-metallic ferromagnetism character, that Cr in the diluted doping limit forms near-midgap deep levels, and that the total magnetization of the cell is 3μ_B per Cr atom, which does not change with Cr concentration. Moreover, we have succeeded in predicting that Al_1-xCr_xN alloys in x=0.0625 has a very high Curie temperature, and find that ferromagnetic exchange interaction between magnetic dopants is short-ranged.