X-RAY AND NEUTRON REFLECTIVITY INVESTIGATIONS OF CO CU MULTILAYERS/

We have studied the effect of low-energy ion beam etching of silicon ( 1 0 0) substrates on the magneto-transport and structural properties o f sputter deposited cobalt/copper multilayers. The films had a nominal structure of 16{1 nm Co/2.1 nm Cu} + 1 nm Pt placing them on the sec ond peak of the oscillatory coupling curve. We show that, as the etchi ng energy is increased from 0 to 1500 eV, the giant magnetoresistance (GMR) decreases from about 19% to about 1%. This is attributed to subt le changes in the him microstructure causing the destruction of antife rromagnetic coupling between the magnetic layers. We present reflectiv ity and X-ray diffraction data which suggest that Fermi surface effect s in the bulk drive the changes in GMR. However, we conclude that spin -dependent scattering at the interfaces may yet be a significant facto r and suggest that the interfacial structure be examined more closely using diffuse reflectivity techniques. (C) 1998 Elsevier Science B.V. All rights reserved.