Electronic Structure and Optical Properties of the Co-doped Anatase TiO$_{2}$ Studied from First Principles

TL;DR

This study uses first-principles calculations to explore how Co doping and oxygen vacancies affect the electronic and optical properties of anatase TiO₂, shedding light on its ferromagnetism at room temperature.

Contribution

It provides a detailed first-principles analysis of how Co doping and oxygen vacancies influence the electronic structure and optical properties of anatase TiO₂, explaining the origin of its ferromagnetism.

Findings

Co is in a low spin state when doped into TiO₂.

Oxygen vacancies enhance ferromagnetism and significantly affect electronic and optical properties.

Results are consistent with experimental data.

Abstract

The Co-doped anatase TiO$_{2}$, a recently discovered room-temperature ferromagnetic insulator, has been studied by the first-principles calculations in the pseudo-potential plane-wave formalism within the local-spin-density approximation (LSDA), supplemented by the full-potential linear augmented plane wave (FP-LAPW) method. Emphasis is placed on the dependence of its electronic structures and linear optical properties on the Co-doping concentration and oxygen vacancy in the system in order to pursue the origin of its ferromagnetism. In the case of substitutional doping of Co for Ti, our calculated results are well consistent with the experimental data, showing that Co is in its low spin state. Also, it is shown that the oxygen vacancy enhances the ferromagnetism and has larger effect on both the electronic structure and optical properties than the Co-doping concentration only.