Structure and annealing of NiMn spin valves

The thermal stability of sputtered NiMn pinned spin valves (NiFe/Co/Cu/Co/N iFe/NiMn) was studied for different Co and Cu thicknesses. The coupling bet ween NiFe and antiferromagnetic NiMn was established by an annealing proces s which also led to a change of magnetoresistance due to diffusion through the Cu layer. Annealing was performed under vacuum in a magnetic field to p revent degradation of the magnetic anisotropy in the antiferromagnet. High angle x-ray diffraction showed a typical shift of the (111) NiMn peak durin g annealing and a structural change with different Co thicknesses. (C) 1999 American Institute of Physics. [S0021-8979(99)34808-8].