Study of the morphological and magnetic structures of nanocrystalline cobalt films obtained by electrodeposition

Cobalt films were electrodeposited at room temperature on polycrystalline gold substrates, using three-electrode system. The investigated films were 14 μm and 23 μm in thickness, as determined by cross-sectional views of the specimens with scanning electron microscopy (SEM). The morphological structure of the films was revealed by SEM and atomic force microscopy (AFM), while the magnetic structure was observed with magnetic force microscopy (MFM). SEM studies showed that the surface morphology of the films consisted of elevations and cavities in the form of stripes, of the order of 100 μm in width, running in the direction parallel to the direction of the current flow during the electrodeposition process. There were also some cracks on the surface of the films. More detailed AFM observations revealed that the morphological structure was composed of nanocrystalline grains, with average sizes of (100 ± 10) nm and (130 ± 20) nm for the films 14 μm and 23 μm thick, respectively. MFM investigations showed the presence of maze domains with magnetization perpendicular to the film plane. The magnetic domains had average sizes of (360 ± 20) nm and (480 ± 30) nm for the films 14 μm and 23 μm thick, respectively.