Ageing effect of the electrolyte on structure and magnetic properties of Co-rich Co-Pt films

Co-rich Co-Pt films have been electrodeposited on Si (100) substrates with a 30 nm thick Cr buffer and a 10 nm Au conducting layer. Films have been deposited on different days after preparing the electrolyte, at current density of 28 mA/cm(2), keeping all other deposition parameters constant. It has been observed from pole figures and magnetic measurements that the age of electrolyte has a significant effect on phase formation and magnetic properties of Co-Pt films. This instability in the deposition process with the age of the electrolyte is attributed to the anodic oxidation of ammonia and citrate in the presence of Co2+ ions, which has a significant influence on the deposition of cobalt based alloys. The reduction of Co2+ can be modify by two ways. First, it is possible that the nature of the complexation of Co2+ is changed because of a decomposition of ammonium citrate and formation of new compounds. Secondly, the new molecules formed in the anodic reaction may decrease the rate of reduction of Co2+ by adsorbing on the cathode surface. These adsorbed products on the cathode surface can influence the structure and magnetic properties of Co-Pt films.