Roles of oxygen vacancies on ferromagnetism in Ni doped In2O3: A hybrid functional study

TL;DR

This study uses hybrid functional first-principles calculations to explore how oxygen vacancies influence the magnetic properties of Ni-doped In2O3, revealing their role in antiferromagnetic coupling and magnetization.

Contribution

It provides a detailed theoretical analysis of oxygen vacancies' impact on magnetic interactions in Ni:In2O3 using hybrid functional calculations, highlighting the superexchange mechanism.

Findings

Ni-doped In2O3 is a ferromagnetic semiconductor.

Oxygen vacancies induce antiferromagnetic coupling between Ni atoms.

Oxygen vacancies reduce the saturation magnetization in experiments.

Abstract

The roles of oxygen vacancies on the electronic and magnetic properties of Ni doped In$_2$O$_3$ have been studied by first-principles calculations based on hybrid functional theory. Our results predict that the Ni-doped In$_2$O$_3$ system displays a ferromagnetic semiconducting character. However, the presence of oxygen vacancies results in antiferromagnetic coupling between the neighboring Ni pair bridged by an oxygen vacancy. The antiferromagnetic coupling is found to arise from the predominant role of superexchange due to the strong Ni 3d-O 2p hybridization. Consequently, the oxygen vacancies play a key role in the lower saturation magnetization of Ni:In$_2$O$_3$ polycrystalline sample, as observed in experiments.