Influence of Pb additive to the spacer layer on the structure and giant magnetoresistance of electrodeposited Co/Cu multilayers

摘要

In an effort to see the possible surfactant effect of Pb on the formation of electrodeposited multilayers, Co/Cu(Pb) multilayers were prepared by this technique and their structure and giant magnetoresistance (GMR) were investigated. The multilayers were deposited from a perchlorate bath with various amounts of Pb2+ ions in the solution. The composition analysis by energy dispersive X-ray spectroscopy revealed that the Pb mole fraction in the deposit varies in a non-monotonous manner with Pb2+ ion concentration. By fitting the measured X-ray diffraction patterns, superlattice satellites could be identified in some of these multilayers. A ferromagnetic-type GMR behavior was observed for Co/Cu(Pb) deposits prepared from baths with small Pb2+ ion concentration, corresponding to the formation of a layered structure. The GMR magnitude decreased from 8 to 10 % with increasing Pb concentration and, also, changed to a superparamagnetic-type GMR; finally, for high Pb2+ ion concentrations, the magnetoresistance behavior turned over to anisotropic magnetoresistance characteristic of bulk materials.