Electrodeposition of Co–Cu–Zn/Cu multilayers: influence of anomalous codeposition on the formation of ternary multilayers

Abstract

Electrodeposited Co–Cu–Zn/Cu multilayers have been prepared with various control modes. It was found in all cases that the Zn content of the magnetic layer is higher than that in the corresponding dc-plated sample. The data of the composition analysis were elucidated by the assumption of anomalous codeposition of Zn and Co. When the less noble layer is deposited, a Zn-rich zone is produced first, then it is covered with a Co-rich layer. If exchange reaction was allowed during the pulse-plating, Co dissolved selectively while the Zn content of the Co-rich layer remained unchanged. The relative resistance of Zn against the exchange reaction is due to the limited accessibility of the Zn-rich zone of the sample rather than electrochemical reasons. The structure of the deposit was analyzed by X-ray diffraction (XRD). It was revealed that Zn incorporation leads to strongly textured deposits with (1 1 1) orientation. The Zn atoms also enlarge the lattice distances of all phases formed. The incorporation of Zn into the magnetic layer of the multilayers decreases the magnetoresistance of the samples.