SPIN-DIFFUSION LENGTHS OF CU1-XNIX USING CURRENT PERPENDICULAR TO PLANE MAGNETORESISTANCE MEASUREMENTS OF MAGNETIC MULTILAYERS

Spin-relaxation effects are generally believed to have a strong influe nce on giant magnetoresistance of ferromagnetic/noble-metal multilayer s. We have measured current perpendicular to plane magnetoresistances (CPP MR's) of sputtered Co/Cu1-xNix multilayers with x=0.06, 0.10, 0.1 4, and 0.23. Our results indicate that the spin-diffusion length of Cu Ni is reduced as the concentration of Ni increases. Spin-diffusion len gths obtained from fitting the CPP MR to Valet-Fert theory are in a go od agreement with theoretical calculations from spin-orbit scattering. Assuming that the permalloy(Py)-Cu interface in Py/Cu multilayers res embles a CuNi alloy, we can conclude that there will be spin-flip scat tering at a Py-Cu interface, but we expect its effect on the MR to be small.