Microstructure and magnetic behavior of electrodeposited CoPt thick films upon annealing

摘要

CoPt films with a thickness about 5-um consisting of a disordered face-centered cubic phase have been prepared by using the electrodeposition technique. X-ray diffraction measurements and transmission electron microscopy studies reveal that the annealed CoPt films possess a nanocomposite microstructure of Al +Ll_0 CoPt and the size and volume fraction of the Ll_0 ordered phase increase with annealing time. A strong magnetic exchange coupling between the Al phase and the Ll_0 ordered phase is observed after annealing for 2.5 h, which yields a large coercivity H_c=14.2 kOe and a high remanence ratio M_r/M_s=0.88 for the nanocomposite thick films of Al +Ll_0 CoPt.