RESISTIVITY ANOMALY IN NONMAGNETIC METALS WITH FERROMAGNETIC INSULATOR PROXIMITY LAYERS

Epitaxial bilayers and multilayers were prepared using the ferromagnet ic 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 resistivit y 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 meas urements showed a clear dichroism for Eu but none for V. Therefore, th e dR/dT discontinuity is attributed to a change in spin-dependent surf ace scattering at the insulator/metal interface caused by the magnetiz ation of the surface layer of Eu++ ions. The difference in temperature between the dR/dT discontinuities between the two metals (and from th e bulk EuO Curie temperature of 70 K) is tentatively attributed to the influence of the Ruderman-Kittel-Kasuya-Yosida (RKK-Y) mechanism.