Spin transport through ferromagnetic|nonmagnetic interfaces at finite temperatures: An ab-initio study of spin-memory loss

The discontinuity of spin currents at an interface is a direct consequence of enhanced spin-orbit splitting. The spin-memory loss (SML) which characterizes this discontinuity is a key to quantitatively understand the effect of interface spin orbit coupling (ISOC) on spin transport. While ISOC can make a significant contribution in a variety of experiments dealing with multilayer ferromagnetic(F)|nonmagnetic(N) geometries, it is usually neglected in their interpretation to avoid introducing too many free parameters. To study devices operating at ambient temperature it is desirable to understand how thermal disorder affects interface behavior. Unfortunately experimental studies of SML have been limited to low temperatures. In this work, we determine the SML, interface resistance and spin-asymmetry parameters as a function of temperature for a Py(Ni₈₀Fe₂₀)|Pt interface. Using first-principles scattering theory, we calculate the conductance as well as local charge and spin currents, modeling temperature-induced disorder within the adiabatic approximation with frozen thermal lattice and (for F materials) spin disorder. Our results for the spin current are then interpreted in terms of a generalized Valet-Fert model in order to extract the above parameters.