Description of spin-polarized current using Boltzmann transport equation

Abstract

Recent discoveries of spin current, spin Hall effect and Rashba effect have attracted a new interest in transport phenomena in multilayer systems. The Fuchs-Sondheimer theory that is based on the Boltzmann transport equation covers the transport phenomena in thin films. Though the paper was released in 1952, the theory is still being used with great success and is in a great agreement with experiments. Within this work, we use this theory for the description of an in-plane current density in a multilayer system Ta/Pt/[Co/Ni]/Pt/Ta. The resistance of the multilayer is measured as the function of the thicknesses of individual layers. Using the Fuchs-Sondheimer model we obtain the material parameters of the layers and the current distribution in the sample. This is of a great importance for multilayers, as the spin phenomena, like spin Hall effect and spin-transfer torque, are proportional to current densities in the vicinity of the interface with ferromagnetic material.