Perpendicular giant magnetoresistance of Co 91Fe 9/Cu exchange-biased spin-valves: further evidence for a unified picture

Abstract

Measurements are reported of the increase in specific resistance, AΔ R, with increasing Co 91Fe 9 layer thickness in current-perpendicular to the plane (CPP) exchange-biased spin-valves (EBSVs) of Co 91Fe 9 and Cu. Analysis of these measurements yields a spin anisotropy parameter for Co 91Fe 9 of β=0.65±0.05, and a spin diffusion length of l CoFe sf=12±1 nm. The value of β agrees reasonably well with those obtained experimentally and theoretically for dilute CoFe alloys, thus providing additional support for a unified picture of spin-polarized transport in CPP-MR and bulk alloys. This value of l CoFe sf, and the previously determined l Py sf for Permalloy, scale approximately inversely with the residual resistivities of the two alloys.