Effect of electrode and EuO thickness on EuO-electrode interface in tunneling spin filter

The effect of electrode material and EuO film thickness on the interface between the two was studied. Of the electrodes examined, yttrium was found to decrease the formation of the nonmagnetic oxide Eu2O3. By decomposing the x-ray absorption spectroscopy (XAS) spectra of the samples with different electrodes against the reference EuO and Eu2O3 spectra, the relative fraction of these two species was quantified. Multilayers with silver electrodes had the highest amount of Eu2O3, about 41%, whereas aluminum had 28% compared to the less than 5% observed for the multilayers with yttrium electrodes. A slight decrease in the fraction of Eu2O3 with increasing EuO thickness was found. Angle dependent XAS measurements, done on 80 angstrom EuO film, indicated the presence of Eu2O3 at high grazing angles which then decreased drastically with decreasing grazing angle. This indicated that the Eu2O3 was localized at the EuO-electrode interface. (C) 2006 American Institute of Physics.