Using the full-potential linearized augmented plane wave method, an investigation

was made of the oxygen vacancy defect-induced ferromagnetism in both rutile and

anatase. It was found that the oxygen vacancy introduced a lattice distortion into

rutile, whereas there was no such significant change in the anatase structure. The

lattice-distorted rutile exhibited an oxygen vacancy-induced ferromagnetic state

with a magnetic moment of 0.22μB in the Ti atom neighbouring the vacancy site,

while only 0.06μB was observed for the Ti atom in anatase. The sizable magnetic

moment due to the oxygen vacancy in rutile was attributed to the charge

redistribution due to lattice distortion. Experimentally measured magnetic

hysteresis curves for undoped rutile and anatase films clearly revealed a

ferromagnetic behaviour at room temperature. The observed magnetic strength of

the rutile samples was found to be larger than that of the anatase samples; in accord

with the theoretical calculations.

The Origin of Oxygen Vacancy Induced Ferromagnetism in Undoped TiO2. D.Kim,

J.Hong, Y.R.Park, K.J.Kim: Journal of Physics - Condensed Matter, 2009, 21[19],

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