Ballistic electron magnetic microscopy studies of magnetization reversal in CoÕCuÕCo trilayer films

We have used ballistic electron magnetic microscopy to image, with nanometer resolution, the magnetization behavior of Co/Cu/Co trilayer films in the presence of a magnetic field. Films prepared both by thermal evaporation and by magnetron sputtering have been studied. In each case we have observed both large, ;500 nm, domain structures, and much smaller, apparently randomly dispersed, regions of magnetic misalignment between the Co layers that persist to fields .100 Oe. We find the details of the ballistic electron transport through the films to be different on small length scales, ;50 nm, for the two types of growth methods. © 2000 American Institute of Physics. @S0021-8979~00!80508-3#