Field-anneal effects on magnetic and magnetoresistive properties of Fe-Mn, Ir-Mn and NiO spin valves

Spin valves with a Co film as a reference layer and with antiferromagnetic Fe-Mn, Ir-Mn and NiO films as pinning layers were deposited in a DC magnetron sputtering system, and annealed in a field parallel, perpendicular or antiparallel to the easy aids of the reference layer. After anneal, their ferromagnetic coupling and unidirectional anisotropy fields, as well as anisotropy and giant magnetoresistance coefficients were characterized at room temperature. Four critical temperatures were determined from variations of these properties with anneal temperatures. These spin valves were evaluated based on these properties and critical temperatures. Approaches to improvements of these spin valves for uses as read sensors were discussed.