Thermal stability of CoFe, Co and NiFe/Co spin valves

The magnetotransport and magnetic properties of three types of spin valves containing CoFe and Co in the free and pinned layers were investigated as a function of annealing temperature. The microchemical changes induced by annealing were correlated with the evolution of spin valve properties. Auger depth profiling and X-ray diffraction revealed that excellent thermal stability up to 220/spl deg/C of the spin valves containing CoFe and Co can be attributed to an improvement in perfection of the as-sputtered, initially compositionally intermixed Co(Fe)/Cu/Co(Fe) and NiFe/Ta interfaces. The best overall thermal stability was exhibited by the 50Ta/20NiFe/30CoFe/23Cu/50CoFe/90FeMn/50Ta (layer thicknesses in /spl Aring/) spin valve. After annealing for 2 hours at 260/spl deg/C, it showed magnetoresistance ratio of 7.5%, exchange pinning field of 165 Oe, interlayer coupling field of /spl sim/11 Oe and easy axis coercivity of <4 Oe.