OBSERVATION OF DOMAIN DYNAMICS IN GIANT MAGNETORESISTIVE CO-CU-BASED POLYCRYSTALLINE MULTILAYERS

A high resolution interference-contrast colloid technique has been use d to investigate domain dynamics associated with the antiferromagnetic (AF)double left right arrow ferromagnetic (F) magnetization reversal processes in polycrystalline Co-Cu-based magnetic multilayers exhibiti ng giant magnetoresistance. The magnetization reversal was found to be local and nonuniform in nature: within each grain reversal occurs by nucleation of one or more reversed domains at its grain boundary, and different grains require different critical applied field values for w all nucleation, and their subsequent motion. Significantly, the domain dynamics associated with F double right arrow AF reversal were found to have different characteristics in comparison with the AF double rig ht arrow F magnetization reversal. These results indicate asymmetrical giant magnetoresistance loop characteristics at the mesoscopic scale. (C) 1997 American Institute of Physics.