Nanoscale physics 

Spin-dependent scattering and a spin transfer torque in magnetic nanostructures with normal metal layers 
Korostil A.M., Krupa M.M.
Department of Physics of Meso- and Nanocrystalline Magnetic Structures, Institute of Magnetism, Nati. Acad. of Sci. of Ukraine and Min. Ed..Sci. of Ukraine. Prospect Vernadsky, 36b, Kiev-03142, Ukraine. 
E-mail: korostilandrii@gmail.com

The problem of the field and current-driven magnetic dynamics in multilayer magnetic nanostructures involves the description of intercoupling between spin transport and dynamical properties related to the spin dependent electron scattering on the interfaces [1]. The latter is exhibited in effects of multiple spin dependent electron scattering between interfaces, spin transfer torque on localized magnetic moments, the effects of spin pumping and spin accumulations [2]. Such effects in magnetic nanostructers with normal metal layers represent special interest due to possibility realization of field and current-induced ultrafast magnetic dynamics. 
The interconnection between the spin current and spin dynamics via the spin-dependent scattering and an accompanying spin torque effect in ferromagnetic/normal metal based magnetic multilayer nanostructure is studied including a high fast out-of-equilibrium spin dynamics. Features of the spin transport and its impact on spin dynamics are described on the basis of the scattering matrix formalism for spin flows. The dependence of the spin torque effect on conductance character of the normal metal layers is considered. The exchange processes between the itinerant and the localized electrons are described by kinetic rate equations for electron-magnon spin-flop scattering. It is shown that the magnon distribution function remains nonthermalized on the relevant time scales of the demagnetization process, and the relaxation of the out-of-equilibrium spin accumulation among itinerant electrons provides the principal channel for dissipation of spin angular momentum from the combined electronic system.

1.	Waintal X., Myers E.B., Brouwer P.W., Ralph D.C. //  Role of spin-dependent interface scattering in generating current-induced torques in magnetic multilayers // Phys. Rev. B.-2000.-62.-P. 12317-12327. 
2.	Tveten E.G., Brataas A., Tserkovnyak Y. Electron-magnon scattering in magnetic heterostructures far out of equilibrium // Phys. Rev.-2015.- 92.- P.-180412(1)-(5).