  Pure spin currents hold promises for an energy-friendlier spintronics. They
can be generated by a flow of charge along a non-magnetic metal having a large
spin-orbit coupling. It produces a spin accumulation at its surfaces,
controllable by the magnetization of an adjacent ferromagnetic layer.
Paramagnetic metals typically used are close to a ferromagnetic instability and
thus magnetic proximity effects can contribute to the observed
angular-dependent magnetoresistance (ADMR). As interface phenomena govern the
spin conductance across the metal/ferromagnetic-insulator heterostructures,
unraveling these distinct contributions is pivotal to full understanding of
spin current conductance. We report here x-ray absorption and magnetic circular
dichroism (XMCD) at Pt-M and (Co,Fe)-L absorption edges and atomically-resolved
energy loss electron spectroscopy (EELS) data of Pt/CoFe2O4 bilayers where
CoFe2O4 layers have been capped by Pt grown at different temperatures. It turns
out that the ADMR differs dramatically, being either dominated by spin Hall
magnetoresistance (SMR) associated to spin Hall effect or anisotropic
magnetoresistance (AMR). The XMCD and EELS data indicate that the Pt layer
grown at room temperature does not display any magnetic moment, whereas when
grown at higher temperature it is magnetic due to interfacial Pt-(Co,Fe)
alloying. These results allow disentangling spin accumulation from interfacial
chemical reconstructions and for tailoring the angular dependent
magnetoresistance.
