Electronic and magnetic properties of V-doped anatase TiO$_{2}$ from first principles

TL;DR

This study uses first-principles calculations to explore the electronic and magnetic properties of vanadium-doped anatase TiO₂, revealing mechanisms behind observed room-temperature ferromagnetism.

Contribution

It demonstrates that V doping induces ferromagnetism through superexchange interactions and magnetic polarons, aligning theoretical predictions with experimental observations.

Findings

V atoms tend to cluster and promote ferromagnetism

DFT+U accurately predicts semiconductor behavior

Magnetic interactions involve superexchange and polarons

Abstract

We report a first-principles study on the geometric, electronic and magnetic properties of V-doped anatase TiO$_{2}$. The DFT+U (Hubbard coefficient) approach predicts semiconductor band structures for Ti$_{1-x}$V$_{x}$O$_{2}$ (x=6.25 and 12.5%), in good agreement with the poor conductivity of samples, while the standard calculation within generalized gradient approximation fails. Theoretical results show that V atoms tend to stay close and result in strong ferromagnetism through superexchange interactions. Oxygen vacancy induced magnetic polaron could produce long-range ferromagnetic interaction between largely separated magnetic impurities. The experimentally observed ferromagnetism in V-doped anatase TiO$_{2}$ at room temperature may originate from a combination of short-range superexchange coupling and long-range bound magnetic polaron percolation.