  Spin currents can modify the magnetic state of ferromagnetic ultrathin films
through spin-orbit torque. They may be generated by means of spin-orbit
interaction by either bulk or interfacial phenomena. Electrical transport
measurements reveal a six-fold increase of the spin-orbit torque accompanied by
a drastic reduction of the spin Hall magnetoresistance upon the introduction of
a Cu interlayer in a Pt/Cu/Co/Pt structure with perpendicular magnetic
anisotropy. We analyze the dependence of the spin Hall magnetoresistance with
the thickness of the interlayer in the frame of a drift diffusion model that
provides information on the expected spin currents and spin accumulations in
the system. The results demonstrate that the major responsible of both effects
is spin memory loss at the interface. The enhancement of the spin-orbit torque
when introducing an interlayer opens the possibility to design more effient
spintronic devices based on materials that are cheap and abundant such as
copper.
