Theoretical investigation of half-metallicity in Co/Ni substituted AlN

TL;DR

This paper investigates the electronic and magnetic properties of Co and Ni substituted AlN in the zinc blende phase, revealing half-metallicity and ferromagnetism due to specific hybridization and state splitting.

Contribution

It provides a theoretical analysis of half-metallicity in Co/Ni substituted AlN, highlighting the origin of magnetic moments and electronic structure in these materials.

Findings

Al0.75Co0.25N and Al0.75Ni0.25N are ferromagnetic with magnetic moments of 4 μB and 3 μB.

These compounds exhibit full spin polarization at the Fermi level, indicating half-metallicity.

The interaction with N-2p states causes splitting of Co/Ni-3d states into t2g and eg states due to tetrahedral symmetry.

Abstract

Results of Co and Ni substituted AlN in the zinc blende phase are presented. For spin up states the hybridized N-2p and Co/Ni-3d states form the valance bands with a bandgap around the Fermi level for both materials, while in the case of the spin down states the hybridized states cross the Fermi level and hence show metallic nature. It is found that, Al0.75Co0.25N and Al0.75Ni0.25N are ferromagnetic materials with magnetic moments of 4 {\mu}B and 3 {\mu}B respectively. The integer magnetic moments and the full spin polarization at the Fermi level make these compounds half-metallic semiconductors. Furthermore it is also found that the interaction with the N-2p state splits the 5-fold degenerate Co/Ni-3d states into t2g and eg states. The t2g states are located at higher energies than the eg states caused by the tetrahedral symmetry of these compounds.