Effects of the surface tension of the electrolyte on magnetic properties of Co-Ni-Mg electrodeposited thin films

We investigate in this work the influence of the surface tension of the electrolyte on the magnetic properties of thin electrodeposited Co-Ni alloy films, in order to accurately control their properties for various technological applications. Co-Ni-Mg films containing (75-82) at.% Co, 3-4 at.% Mg, balance Ni, were electrodeposited on aluminium substrates using a complex solution containing ions of Co, Ni and Mg. Sodium laurylsulphate (as surface-active agent), and sodium saccharin (as inhibitor agent) were used to control the surface tension of the solution. The adsorption of some dipoles of these substances on the electrolytetfilm interface (studied by square-wave polarography) results in changes in the film morphology (investigated by AFM). Consequently, the magnetic properties (studied by torsion magnetometry and an induction method) are changed as a function of the additive concentrations. The magnetic characteristics are in the range H-c = (5 - 70) kA/m, B-r/B-s = 0.2 - 0.95, and K-eff = -20 x 10(4) J/m(3) to +40 x 10(4) J/m(3).