Effect of Surface Roughness on the Magnetism, Nano-indentation, Surface Energy, and Electrical Properties of Co₆₀Fe₂₀Dy₂₀ Films on Si (100) Substrate

In this study, we focused on depositing a target material, cobalt-iron-dysprosium (Co₆₀Fe₂₀Dy₂₀), onto silicon (Si) (100) substrates with thickness varying from 10 nm to 50 nm through a direct-current (DC) magnetron sputtering technique. The subsequent step involved subjecting the samples to an hour-long annealing process in a vacuum annealing furnace at temperatures of 100°C, 200°C, and 300°C. To assess the elemental composition of the CoFeDy films, energy-dispersive X-ray spectroscopy (EDS) was employed. An observed trend indicated an increase in low-frequency alternating-current magnetic susceptibility (χ_ac) with the increasing thickness. Remarkably, the CoFeDy films exhibited their peak χ_ac following annealing at 300°C, with an optimal resonance frequency of 50 Hz. After annealing at 300°C, the CoFeDy film’s surface energy peaked at 50 nm. The magnetic, electrical, and adhesive properties of the CoFeDy films were notably influenced by surface roughness at different annealing temperatures. Atomic force microscopy (AFM) analysis revealed a gradual reduction in film roughness post-annealing, corresponding to smoother surfaces indicative of a weaker domain wall pinning effect, heightened carrier conductivity, and increased liquid spreading. Collectively, these outcomes contributed to diminished χ_ac, reduced electrical resistance, and enhanced adhesion.