Current-perpendicular-to-plane spin transport properties of CoFe alloys: Spin diffusion length and scattering asymmetry

Abstract

From measurements of the current-perpendicular-to-plane magnetoresistance of magnetic multilayers and exchange-biased spin-valves combining the ferromagnetic (F) alloys Co50Fe50 and Co70Fe30 with the nonmagnetic metal Cu, we extract values of the bulk scattering asymmetry, beta(F), the spin-diffusion length, l(sf)(F), the interface scattering asymmetry, gamma F/cu, and twice the enhanced specific resistance, 2AR*(F/cu). The parameters of the two alloys lie within mutual uncertainties of each other. The values of beta(F)similar to 0.88 are unusually large, those of l(sf)(F)similar to 10 nm are moderate and consistent with values for other F-alloys, and those of 2ARF*(F/Cu)similar to 0.6 f Omega m(2) and gamma(F/Cu)similar to 0.6 are both less than those for Co/Cu. We do not need to include any spin-flipping at the F/Cu interfaces to fit our data. (C) 2010 American Institute of Physics. [doi:10.1063/1.3436584]