Thermal stability of spin valve with NiO/α-Fe/sub 2/O/sub 3/ bilayer antiferromagnets

To enhance the thermal stability of the NiO pinning layers for spin valves, /spl alpha/-Fe/sub 2/O/sub 3/ layers, of which the Neel temperature is 680/spl deg/C for bulk, are deposited on NiO layers. With 15-80 /spl Aring/ thick /spl alpha/-Fe/sub 2/O/sub 3/ layers on NiO layers, an exchange anisotropy field about five times larger than that of NiO/NiFe is obtained after 250/spl deg/C thermal annealing. Spin valve multilayers with NiO//spl alpha/-Fe/sub 2/O/sub 3/ antiferromagnets show about 12% MR ratio. After 150/spl deg/C annealing, the MR ratio changes less than 20% for patterned spin valve multilayers with abutted junctioned hard magnets.