Origins of coercivity increase in annealed symmetric spin valves

Measurements of the effects of annealing on symmetric Co/Cu spin valves and similar structures show increased coercivity, increased ferromagnetic resonance linewidth and reduced moment. Low angle X-ray reflectivity measurements indicate that there is some oxidation throughout the thickness of the metal films during annealing. The layer structure, as determined from low-angle X-ray reflectivity and magnetoresistance values is only weakly affected by annealing at 250 C. We conclude from these results that the Cu/Co interfaces are not strongly affected, and we suspect that the thermally induced changes in these include partial oxidation which occurs mainly in the grain boundaries, which lie perpendicular to the film plane.