Microstructure and magnetic properties of electrolessly deposited Co-S thin films

Thin films of Co-S, 200–400 nm thick, containing 0–17 at.% sulphur have been prepared by electroless deposition onto polycrystalline copper substrates from basic baths of various composition at 90°C. The grain morphology and phase composition was studied by X-ray diffraction and scanning electron microscopy. The films are microcrystalline or microcrystalline-amorphous materials. The average size of small grains lies in the range of 119–195 Å, depending on sulphur content. The S content dependencies of saturation magnetization, squareness ratio and coercivity can be satisfactorily explained that we consider magnetic magnitude values are a consequence of the microstructure of films. Saturation magnetization linear decreases with sulphur content increasing. The in-plane coercivity increases with increasing sulphur content from 10 to 22 kA m−1. The in-plane squareness ratio decreases with increasing sulphur content but remains sufficiently high (>0.65). The study of the magnetic properties indicates that the high sulphur content films have smaller grains at a higher thickness than do the low sulphur content films. The microstructure and magnetic properties suggest that films behave as a random assembly of interacting uniaxial particles embedded in an insulating matrix.