Theoretical study on copper's energetics and magnetism in TiO2 polymorphs

TL;DR

This study uses density functional theory to explore the electronic and magnetic properties of copper-doped TiO2 polymorphs, revealing stable substitutional doping and potential high-temperature ferromagnetism, with differences between anatase and rutile phases.

Contribution

It provides a detailed theoretical analysis of copper doping effects on TiO2's magnetism and energetics, highlighting phase-dependent magnetic interactions and dopant clustering tendencies.

Findings

Copper prefers substitutional sites in both polymorphs.

Ferromagnetism may persist above room temperature in anatase.

Rutile exhibits short-range magnetic interactions.

Abstract

We carried out density functional theory calculations to model the electronic structure and the magnetic interactions in copper doped anatase and rutile titanium dioxide in order to shed light on the potential of these systems as magnetic oxides using different density functional schemes. In both polymorphs copper dopant was found to be most stable in substitutional lattice positions. Ferromagnetism is predicted to be stable well above room temperature with long range interactions prevailing in the anatase phase while the rutile phase exhibits only short range superexchange interaction among nearest neighbouring Cu ions. Additionally, energetic evaluation of dopants in scattered and compact configurations reveals a dopant clustering tendency in anatase TiO2.