Oxygen Vacancy Induced Ferromagnetism in V$_2$O$_{5-x}$

TL;DR

This study uses ab initio calculations to show that oxygen vacancies in V2O5-x induce ferromagnetism by creating spin-polarized V d-electron states, leading to half-metallic ferromagnetism.

Contribution

It demonstrates that oxygen vacancies can induce ferromagnetism in V2O5-x and elucidates the electronic mechanism behind this phenomenon.

Findings

Oxygen vacancies induce ferromagnetism proportional to vacancy concentration.

Vacancy-induced electrons occupy V d_{xy} band, causing spin polarization.

The material exhibits half-metallic ferromagnetism due to vacancy effects.

Abstract

{\it Ab initio} calculations within density functional theory with generalized gradient approximation have been performed to study the effects of oxygen vacancies on the electronic structure and magnetism in undoped V$_2$O$_{5-x}$ ($0 < x < 0.5$). It is found that the introduction of oxygen vacancies would induce ferromagnetism in V$_2$O$_{5-x}$ with the magnetization being proportional to the O vacancy concentration $x$. The calculated electronic structure reveals that the valence electrons released by the introduction of oxygen vacancies would occupy mainly the neighboring V $d_{xy}$-dominant band which then becomes spin-polarized due to intra-atomic exchange interaction, thereby giving rise to the half-metallic ferromagnetism.