Magnetism and heterogeneity of Co in anatase Co:TiO2 magnetic semiconductor

摘要

Using x-ray magnetic circular dichroism u0001XMCDu0002, x-ray absorption spectroscopy u0001XASu0002, andnenergy filtered transmission electron microscopy, we provide evidence for a heterogeneous Condistribution in anatase Co:TiO2 magnetic semiconductor having a low Co concentration u00011.4 at. %u0002.nMultiplet structure due to Co2+ is observed in XAS spectra, but suppressed due to the coexistencenof metallic Co clusters and substitutional Co ions, whereas XMCD spectra resemble metallic Co.nThe presence of Co2+ can be correlated with earlier observations of impurity band conduction andnKondo behavior, whereas metallic Co clusters contribute to the ferromagnetism and anomalous Hallneffect. © 2010 American Institute of Physics. u0003doi:10.1063/1.3327805