Effect of non-magnetic impurities on the magnetic states of anatase TiO${}_2$

Abstract

The electronic and magnetic properties of TiO${}_2$, TiO${}_{1.75}$, TiO${}_{1.75}$N${}_{0.25}$, and TiO${}_{1.75}$F${}_{0.25}$ compounds have been studied by using \emph{ab initio} electronic structure calculations. TiO${}_2$ is found to evolve from a wide-band-gap semiconductor to a narrow-band-gap semiconductor to a half-metallic state and finally to a metallic state with oxygen vacancy, N-doping and F-doping, respectively. Present work clearly shows the robust magnetic ground state for N- and F-doped TiO${}_2$. The N-doping gives rise to magnetic moment of $\sim$0.4 ${\mu }_B$ at N-site and $\sim$0.1 ${\mu }_B$ each at two neighboring O-sites, whereas F-doping creates a magnetic moment of $\sim$0.3 ${\mu }_B$ at the nearest Ti atom. Here we also discuss the possible cause of the observed magnetic states in terms of the spatial electronic charge distribution of Ti, N and F atoms responsible for bond formation.

11 pages, 4 figures To appear J. Phys.: Condens. Matter

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