ORIGINS OF COERCIVITY INCREASE IN ANNEALED SYMMETRICAL SPIN VALVES

Measurements of the effects of annealing on symmetric Co/Cu spin valve s and similar structures show increased coercivity, increased ferromag netic resonance linewidth and reduced moment. Low angle x-ray reflecti vity measurements indicate that there is some oxidation throughout the thickness of the metal films during annealing. The layer structure, a s determined from low-angle x-ray reflectivity and magnetoresistance v alues 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 samples includ e partial oxidation which occurs mainly in the grain boundaries, which lie perpendicular to the film plane.