SPIN-DEPENDENT SCATTERING IN THE NONMAGNETIC LAYERS OF ANNEALED CO CUMULTILAYERS/

Annealing a multilayer is expected to promote diffusion at the interfa ces. We have found that the interface roughness and giant magnetoresis tance of Co/Cu (111) multilayers, grown by molecular-beam epitaxy on s apphire substrates, remain unchanged during anneals of up to 320 degre es C despite the zero-field resistivity having doubled. We explain thi s large increase in resistivity as due to the formation of an alloy be tween the top Cu layer of the multilayer and the Au protective cap. We propose that scattering in the AuCu alloy is spin dependent. We discu ss this idea in the light of mean free path effects and the density of states of the entire sample. (C) 1996 American Institute of Physics.