Half-metallic ferromagnetism in Ca-doped AlN from first-principles study

Motivated by recent reports on high Curie temperature in nonmagnetic metals doped semiconductor, we study 6.25% Ca substituted aluminium nitrides using a full-potential density-functional method. The Ca-doped AlN is found to be a half-metallic ferromagnet with 100% carrier spin polarization at the Fermi level. The magnetic moments are localized within the CaN4 tetrahedron, and a net magnetic moment of 1μB is found per supercell. At a Ca concentration of 12.5%, total energy calculations show that the ferromagnetic state is 32.6 meV lower than the antiferromagnetic state, and Curie temperature around 300 K can be expected. Since there is no magnetic element in this compound, Ca-doped AlN appears to be a promising dilute magnetic semiconductor free from magnetic precipitate and may have potential applications in the field of spintronics.