We electroplated Fe-Co films in a citric-acid-based plating bath with saccharin and sodium lauryl sulfate and evaluated the magnetic properties of the films. The Fe content in the film can be readily controlled by the change in the ratio of the Fe reagent and the Co one, and the Fe content could be obtained from 10 to 90 at.% in our experimental conditions. The change in the saturation magnetization over the Fe content of the film almost agreed with the expected change from the Slater-Pauling curve. The coercivity decreased with increasing the Fe content. From the structural analysis, we found that the grain size reduced with increasing the Fe content, and the grain refinement effect works effectively to reduce the coercivity.
