Magnetization and impedance measurements of multilayer Co/Cu structures in millimeter waveband

The saturation magnetization of Co/Cu multilayer structures and individual Co films 1.0–4.0 nm thick have been studied both by electron spin resonance technique and by vibrating sample magnetometer method. The results of static and dynamic measurements are in good agreement. It was found that the saturation magnetization of Co layers imbedded in a multilayer structure was greater than the magnetization of individual films and tended to the value of bulk material. The saturation magnetization of multilayer structure with thickness of nonmagnetic Cu interlayer varying from 1.7–10 nm have been investigated for samples both with and without Fe-buffer layer. For the first case Co saturation magnetization has decreased with increase of nonmagnetic interlayer in contrast to similar samples without buffer. The measurements of impedance characteristics have been carried out for the multilayers Fe(6 nm)/[Co(tC)/ Cu(2 nm)]8 (t=1, 2, 3 nm) in the millimeter waveband (at n ¼ 44 GHz). The transmission coefficient dependence on the external static magnetic field for a waveguide containing the multilayer specimen was found to be the same as the dependence of direct current giant magnetoresistance of the mentioned specimen. r 2003 Elsevier Science B.V. All rights reserved.