Domain structures of MOCVD cobalt thin films

Metal-organic chemical vapour deposition (MOCVD) has been used to deposit crystalline films of cobalt metal with a strong crystalline texture. The process parameters were varied to control the grain size, while retaining this texture and a hexagonal habit. These films behave as typical ferromagnetic films, dominated by a balance between shape anisotropy and surface anisotropy, leading to in-plane remanence for films of thickness below 50 nm and a perpendicular component to the anisotropy for thicker films. The domain patterns studied by MFM reflect the in-plane magnetization for the thinner films and the perpendicular anisotropy in the thicker cases, leading to stripe domains. When the grain width is sufficient to support single domains under DC remanent conditions the shape of the magnetic domains is dominated by the grain size and morphology. This occurs for grains around 250 nm across or wider. Some of the largest grains can support a domain wall.