The role of vacancies, impurities and crystal structure in the magnetic properties of TiO2

TL;DR

This study uses ab initio calculations to explore how vacancies, impurities, and crystal structure influence the magnetic properties of TiO2 in rutile and anatase phases, revealing the effects of different defects and dopants.

Contribution

It provides a detailed analysis of the impact of various defects and crystal structures on TiO2's magnetism, highlighting the behavior of Co and Cu impurities and vacancy effects.

Findings

Co impurities maintain magnetic moments regardless of concentration.

Cu impurities show magnetism at low concentrations, disappearing at higher levels.

Vacancies and structural strain can induce magnetism in undoped TiO2.

Abstract

We present an ab initio study of pure and doped TiO2 in the rutile and anatase phases. The main purpose of this work is to determine the role played by different defects and different crystal structures in the appearance of magnetic order. The calculations were performed for varying impurity and vacancy concentrations in both TiO2 structures. For Co impurities the local magnetic moment remained almost independent of the concentration and distribution while for Cu this is not the case, there is magnetism for low concentrations that disappears for the higher ones. Impurity-impurity interactions in both structures favor linear ordering of them. Magnetism in un-doped samples appears for certain vacancy concentrations and structural strain.