The observation of the anomalous Hall effect (AHE) in Co-doped TiO2 ferromagnetic semiconductor in the anatase phase is reported. An AHE is observed with magnetic hysteresis consistent with remanence and coercivity obtained from magnetometry data. The anatase films also have reasonable mobility (∼17cm2∕Vs) at room temperature and carrier density of ∼5×1018cm−3. The AHE in such films with relatively low carrier density gives prospects to test whether the ferromagnetism in this oxide semiconductor is carrier mediated using a field effect device configuration.

We have investigated the effects of modification of the SrTiO3/Co interface as well as the SrTiO3 barrier on the tunnel magnetoresistance TMR of La0.67Sr0.33MnO3/SrTiO3/Co junctions. Modification was realized by the introduction of one atomic layer of either TiO2 or SrO at the SrTiO3/Co interface. Barriers with different oxygen content were also studied. In these structures we have observed positive as well as negative TMR, with a trend towards positive TMR for junctions with interfacial SrO and/or more oxygen-deficient barriers. This work offers more insight into the SrTiO3/Co tunnel spin polarization and its sign.