Influence of oxygen and copper in electrodeposited FePt films

Abstract Electrodeposition can be used to prepare hard magnetic films with a coercivity up to 1.1 T. Nevertheless, as-deposited and vacuum-annealed films exhibit a magnetization much lower than expected. This is caused by 30–35 at% oxygen present in the films after electrodeposition. Annealing in hydrogen leads to a decrease of the oxygen content to about 10 at%, explaining the significantly higher magnetization obtained in hydrogen-annealed films. The remaining iron oxide grains are located particularly at grain boundary triple points. During annealing, Cu diffuses from the buffer layer into the film and is detected along the grain boundaries. Hence, this microstructure can be favourable for a high coercivity.