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

摘要

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 Eu_2O_3. By decomposing the x-ray absorption spectroscopy (XAS) spectra of the samples with different electrodes against the reference EuO and Eu_2O_3 spectra, the relative fraction of these two species was quantified. Multilayers with silver electrodes had the highest amount of Eu_2O_3, about 41 percent, whereas aluminum had 28 percent compared to the less than 5 percent observed for the multilayers with yttrium electrodes. A slight decrease in the fraction of Eu_2O_3 with increasing EuO thickness was found. Angle dependent XAS measurements, done on 80 A EuO film, indicated the presence of Eu_O_3 at high grazing angles which then decreased drastically with decreasing grazing angle. This indicated that the Eu_2O_3 was localized at the EuO-electrode interface.