Investigation of thermally evaporated nanocrystalline thin cobalt films

In this paper, a study has been made of nanocrystalline thin cobalt films with thicknesses in the range from 10 to 60 nm. The films were thermally evaporated at incidence angle of 0° in a vacuum of about 10− 5 mbar. The morphological structure of the films consists of nanocrystalline grains regular in shape and densely packed. As the film thickness is increased from 10 to 60 nm, the average grain size increases from 22.0 to 28.9 nm. The films crystallize mainly in the hexagonal close-packed phase of cobalt. The magnetic structure is composed of domains. In films with thicknesses in the range from 10 to 40 nm, the domains are magnetized in the plane of the film, while films with thicknesses of 50 and 60 nm possess both inplane and perpendicular magnetization components. The domains with inplane magnetization are irregular in shape and typically from a few to 10 mm in size, whereas the domains with perpendicular magnetization form a fine maze stripe pattern of the order of 100 nm in width.