Temperature dependence of giant magnetoresistance and magnetic properties in electrodeposited Co-Cu/Cu multilayers: The role of superparamagnetic regions

摘要

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 (FM) and superparamagnetic (SPM) 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 Cu) leading to the occurrence of SPM regions. The results are discussed also in the framework of interacting SPM regions.