Magnetoresistance and surface roughness study of the initial growth of electrodeposited Co/Cu multilayers

摘要

The giant magnetoresistance (GMR) effect has been widely investigated onelectrodeposited ferromagnetic/non-magnetic (FM/NM) multilayers generallycontaining a large number of bilayers. In most applications of the GMR effect,layered structures consisting of a relatively small number of consecutive FMand NM layers are used. It is of great interest, therefore, to investigate theinitial stages of GMR multilayer film growth by electrodeposition. In thepresent work we have extended our previous studies on ED GMR multilayers tolayered structures with a total thickness ranging from a few nanometers up to70 nm. The evolution of the surface roughness and electrical transportproperties of such ultrathin ED Co/Cu layered structures was investigated.Various layer combinations were produced including both Co and Cu either asstarting or top layers in order (i) to see differences in the nucleation of thefirst layer and (ii) to trace out the effect of the so called exchangereaction. Special attention was paid to measure the field dependence of themagnetoresistance, MR(H) in order to derive information for the appearance ofsuperparamagnetic regions in the magnetic layers. This proved to be helpful formonitoring the evolution of the layer microstructure at each step of thedeposition sequence.