Theoretical study of magnetic ordering and electronic properties of Ag xAl 1− x N compounds

Abstract

Ferromagnetic ordering of silver impurities in the AlN semiconductor is predicted by plane-wave ultrasoft pseudopotential and spin-polarized calculations based on density functional theory (DFT). It was found that an Ag impurity atom led to a ferromagnetic ground state in Ag 0.0625Al 0.9375N, with a net magnetic moment of 1.95 μ B per supercell. The nitrogen neighbors at the basal plane in the AgN 4 tetrahedron are found to be the main contributors to the magnetization. This magnetic behavior is different from the ones previously reported on transition metal (TM) based dilute magnetic semiconductor (DMS), where the magnetic moment of the TM atom impurity is higher than those of the anions bonded to it. The calculated electronic structure band reveals that the Ag-doped AlN is p -type ferromagnetic semiconductor with a spin-polarized impurity band in the AlN band gap. In addition, the calculated density of states reveals that the ferromagnetic ground state originates from the strong hybridization between 4 d -Ag and 2 p -N states. This study shows that 4 d transition metals such as silver may also be considered as candidates for ferromagnetic dopants in semiconductors.