An analysis of both magnetic and magnetotransport properties is presented for electrodeposited multilayers prepared intentionally under conditions to make the superparamagnetic (SPM) magnetization contribution comparable to or larger than the ferromagnetic term. Based on a model elaborated for the giant magnetoresistance (GMR) of granular metals [N. Wiser, J. Magn. Magn. Mater. 159, 119 (1996); B. Hickey et al., Phys. Rev. B. 51, 667 (1995)], it is shown that in such multilayers both the magnetization and the GMR can be decomposed into ferromagnetric and superparamagnetic contributions where the latter term is described by a Langevin function. The size of the SPM regions estimated from the experimental data is in the nanoscale regime. It is believed that the method applied here gives a quantitative answer to the problem of the often observed nonsaturating behavior of GMR in multilayers. Electrodeposited multilayers are particularly prone to this feature although the occurrence of SPM regions is quite common in multilayers prepared by any technique. Therefore, this type of analysis should help better understanding of the factors influencing the GMR of multilayer films.

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We have shown recently that both the magnetization and the magnetoresistance of electrodeposited Co-Cu/ Cu multilayers can be decomposed by assuming the presence of both ferromagnetic ͑FM͒ and superparamagnetic ͑SPM͒ regions in the magnetic layers. In the present work, for two selected samples, one with a large SPM and another one with a large FM contribution to the giant magnetoresistance, low temperature magnetic and magnetoresistance measurements were performed in order to reveal the evolution of the FM and SPM terms with temperature. The average apparent magnetic moment of the SPM regions deduced from the two sets of data showed a good agreement. The role of electrochemical processes in the formation of the SPM regions is discussed. An attempt has also been made to elaborate on some models for the spatial distribution of the constituent elements ͑Co and Cu͒ leading to the occurrence of SPM regions. The results are discussed also in the framework of interacting SPM regions.