Giant Magnetoresistance of Spin Valve Films with NiO Antiferromagnetic Films

The magnetic and magnetoresistive properties of films having spin valve structures were investigated. The basic structure of such films consists of two ferromagnetic layers separated by a Cu layer. One of the ferromagnetic layers is strongly biased by an NiO antiferromagnetic film in direct exchange contact with it. Spin valve films having an NiO/NiFe/Cu/NiFe structure exhibit good sensitivity, and the MR ratio (Δρ/ρ) is 4% in an applied field of 10 Oe. Films with a layered NiO/NiFe/Cu/NiFe/Cu/NiFe/NiO structure have an MR ratio of 7% in a field of 10 Oe. On the other hand, NiO/NiFe/Co/Cu/Co/NiFe films exhibit an MR ratio of 6% to 7.5%. The thermal stability of spin valve films was also studied.