Ballistic electron magnetic microscopy studies of magnetization reversal in Co/Cu/Co trilayer films

We have used ballistic electron magnetic microscopy to image, with nanomete r resolution, the magnetization behavior of Co/Cu/Co trilayer films in the presence of a magnetic field. Films prepared both by thermal evaporation an d by magnetron sputtering have been studied. In each case we have observed both large, similar to 500 nm, domain structures, and much smaller, apparen tly randomly dispersed, regions of magnetic misalignment between the Co lay ers that persist to fields > 100 Oe. We find the details of the ballistic e lectron transport through the films to be different on small length scales, similar to 50 nm, for the two types of growth methods. (C) 2000 American I nstitute of Physics. [S0021-8979(00)80508-3].