First-Principles Study of Antiferromagnetic Superexchange Interactions Between TiAl-VN Complexes in AlN

The structural, electronic, and magnetic properties of pure and Ti doped w-AlN were investigated using density functional theory with motivation to explore the properties of Ti-Al-V-N complex in the matrix. A substitutional Ti dopant with cationic Al atom at nearest neighbor lattice site of V-N was incorporated to form Ti-Al-V-N complex in AlN. The electronic properties of the material revealed that Ti-Al-V-N complex is energetically favorable in AlN and possessed a stable spin-triplet (3)A(2) ground state and doubly degenerate E-3 excited state. A charge transfer from nitrogen vacancy towards Ti dopant was observed which was responsible to increase spin polarization in the electronic structure of AlN host material. Two intermediate band peaks due to hybridized Ti-3d states with N-2p states were seen in the forbidden region narrowing the bandgap of AlN. A local magnetic moment of 2.068 mu(B) was found for the Ti-Al-V-N complex in AlN that was reduced to 0.664 mu(B) on doubling Ti-Al-V-N complex. Hence, Ti-Al-V-N complexes in AlN prefer to couple antiferromagnetically, switched by superexchange interactions between them. Our results show that Ti-Al-V-N complex in AlN may be a robust candidate for applications in optoelectronics and antiferromagnetic spintronics devices.

Automated summary

The structural, electronic, and magnetic properties of pure and Ti doped w-AlN were investigated. It was found that Ti-Al-V-N complex in AlN is energetically favorable, possesses stable spin-triplet ground state, and shows enhanced spin polarization. The complex exhibits strong antiferromagnetic coupling.