RESISTIVITY ANOMALY IN NONMAGNETIC METALS WITH FERROMAGNETIC INSULATOR PROXIMITY LAYERS

Epitaxial bilayers and multilayers were prepared using the ferromagnetic insulator EuO and the metals V and Ag. For metal films of thickness 10 nm or less, there is a sharp change in the slope of the resistivity versus temperature, which occurs at 86 K for EuO/V specimens and at 50 K for EuO/Ag specimens. Soft x-ray magnetic circular dichroism measurements showed a clear dichroism for Eu but none for V. Therefore, the dR/dT discontinuity is attributed to a change in spin-dependent surface scattering at the insulator/metal interface caused by the magnetization of the surface layer of Eu++ ions. The difference in temperature between the dR/dT discontinuities between the two metals (and from the bulk EuO Curie temperature of 70 K) is tentatively attributed to the influence of the Ruderman-Kittel-Kasuya-Yosida (RKK-Y) mechanism.