Angle-dependent magnetoresistance of Pt/EuO_1-x thin films

Europium monoxide (EuO) has attracted a great deal of attention in spintronic research due to its unique ferromagnetic and semiconducting properties. Here, we have prepared Pt/EuO thin films by pulsed laser deposition. We study the magnetic and transport properties as a function of temperature and field. The magnetic data shows enhanced Curie temperature to 140 K, which is a signature of oxygen deficiency. Transport measurements reveal a metal-insulator transition below 70 K associated with the ferromagnetic ordering of EuO. Angle-dependent magnetoresistance exhibits behavior that cannot be explained solely on the basis of anisotropic magnetoresistance of EuO: rather, the MR shows a strong angular dependence as the magnetic field, H, is rotated from in-plane to perpendicular-to-plane, while keeping H perpendicular to the current – a feature consistent with spin Hall magnetoresistance. We discuss the possible origins of the angular dependence by considering the strong spin-orbit coupling present in the system, magnetic proximity effect, interface properties, and the hetero-structure nature of the films.