Additive effects in multilayer electrodeposition: Properties of Co-Cu/Cu multilayers deposited with NaCl additive

Electrodeposited Co-Cu/Cu multilayers have been produced with current contr ol from a sulfate bath with and without NaCl as an additive. The addition o f NaCl decreases the current efficiency of the multilayer deposition and re sults in multilayers with lower GMR and higher electrical resistivity than the chloride-free bath. The grain size of the deposit and the degree of ori entation also decreases if the additive is present. It has been concluded t hat the adsorption of chloride, the formation of copper(I) intermediate, th e change in the deposition mechanism, the increase in nucleation rate, and the occurrence of a non-Faradaic current transient all contribute to the en hancement of the structural disorder that leads to the loss in GMR. Some ge neral conclusions have also been formulated about the role of additives in electrodeposition baths, especially concerning the differences in d.c. plat ing and pulse-plating.