Spin heat accumulation and its relaxation in spin valves

We study the concept of spin heat accumulation in excited spin valves, more precisely the effective electron temperature that may become spin dependent, both in linear response and far from equilibrium. A temperature or voltage gradient create nonequilibrium energy distributions of the two spin ensembles in the normal-metal spacer, which approach Fermi-Dirac functions through energy relaxation mediated by electron-electron and electron-phonon coupling. Both mechanisms also exchange energy between the spin subsystems. This interspin energy exchange may strongly affect thermoelectric properties of spin valves, leading, e.g., to violations of the Wiedemann-Franz law.