Boltzmann transport study of bulk and interfacial spin depolarization effects in spin valves

Abstract

A theoretical model is proposed to analyze both bulk and interfacial spin depolarization effects on the magnetoresistance (MR) of nanoscale spin valves (SVs). The model is based on the spin coupled Boltzmann transport equations where the momentum spin relaxation arising from spin flip and non-spin-flip scattering are considered. In the boundary conditions we include the parameter q which denotes the interfacial spin flip probability, while bulk spin depolarization is characterized by the ratio r of spin flip to non-spin-flip scattering times. We consider a typical FeCrFe pseudo-SV trilayer, and calculate the current for parallel and antiparallel alignments, to deduce the MR. A decreasing trend in MR is observed with an increase in either r or q, with the dependence on q being more pronounced. We also studied the combined effect of interfacial diffusive scattering (described by parameters Ns and D) and spin flip scattering. We found that although diffusive scattering generally results in an improvement in MR, this is more than offset by the MR suppression effect arising from spin flip scattering. © 2008 American Institute of Physics.