ANALYSIS OF SCATTERING LENGTHS IN CO CU/CO AND CO/CU/CO/CU SPIN-VALVES USING A RU BARRIER/

We use uncoupled Co/Cu/Co and Co/Cu/Co/Cu spin-valve structures with a Ru barrier shifted through the top Co and Cu layer, respectively, to measure the longest of the electron mean free paths in Co and Cu as or iginally suggested by Parkin. From semiclassical transport calculation s and careful analysis of the magnetoresistance data we conclude that the exponential behavior of Delta G is uniquely related to the longest of the Co and Cu mean free paths under the condition of effective spi n-dependent filtering at the interfaces or in the bulk of the Co. In t his regime we have compared lambda(long) in Co and Cu with bulk conduc tivities (proportional to lambda(short)+lambda(long)), yielding no str ong evidence for bulk spin-dependent scattering in Co.