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Room-Temperature Ferromagnetism in Co-Doped TiO$_2$ Anatase: Role of Interstitial Co

W. T. Geng·K. S. Kim
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Abstract

TiO$_2$ anatase doped with Co has been recently reported to exhibit room-temperature ferromagnetism. $Ab$ $initio$ study on substitutional Co doping, however, yielded much larger magnetic moment for Co than experiment. Our calculations based on density-functional theory show that the substitutional Co ions incorporated into TiO$_2$ anatase tend to cluster and then the neighboring interstitial tetrahedral sites become energetically favorable for Co to reside, yielding a local environment more like Co$_3$O$_4$ than CoTiO$_3$. The interstitial Co destroys the spin-polarization of the surrounding substitutional Co but enhances the stability of the ferromagnetism significantly. In the absence of carriers, this room-temperature ferromagnetism can only be accounted for by superexchange interaction.

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W. T. Geng, K. S. Kim. 2003-06-15. Room-Temperature Ferromagnetism in Co-Doped TiO$_2$ Anatase: Role of Interstitial Co. https://arxiv.org/abs/cond-mat/0306389

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