Resistivity anomaly in nonmagnetic metals with ferromagnetic insulator proximity layers

Epitaxial bilayers and multilayers were prepared using the ferromagnetic insulator EuO and the metals vanadium and silver. For metal films of thickness 10 nm or less, there is a sharp change in the slope of the resistivity versus temperature curve, which occurs at 86K for EuO/V specimens and at 50K for EuO/Ag specimens. Soft x-ray magnetic circular dichroism measurements showed a clear dichroism for europium 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 exp ++ ions. The difference in temperature between the dR/dT discontinuities between the two metals (and from the bulk EuO Curie temperature of 70K) is tentatively attributed to the influence of the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism.