Effect of annealing and roughness on the magnetic-optical, adhesive, nano-mechanical, and electrical properties of Co60Fe20Dy20 films

Abstract

The structural, magnetic, optical, and adhesion properties of Cobalt-Iron-Dysprosium (CoFeDy) films were investigated in this study. Glass substrates were coated with a Co₆₀Fe₂₀Dy₂₀ alloy via sputtering, with a thickness ranging from 10 nm to 50 nm. Subsequently, the films underwent annealing at temperatures of 100 °C, 200 °C, and 300 °C for one hour. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the deposited CoFeDy films under four distinct conditions. Notably, a thickness-dependent increase in low-frequency alternate-current magnetic susceptibility (χ_ac) was observed. After annealing at 300 °C, CoFeDy films exhibited the highest χ_ac compared to other temperatures. Surface roughness exhibited a decreasing trend with rising annealing temperature, as observed through atomic force microscopy (AFM) experiments. The maximum surface energy of CoFeDy films was achieved at a thickness of 50 nm following annealing at 300 °C. Higher surface energy was indicative of stronger adhesion efficiency. Furthermore, lower resistance and sheet resistance values were obtained through annealing at higher temperatures, suggesting that increasing thickness and reducing electron transport barriers enhanced electron conductivity. As film thickness increased, transmittance decreased due to the thickness effect, suppressing the photon signal. Consequently, rougher surfaces were associated with improved performance in magnetism, electrical adhesion, and optics, attributed to reduced domain pinning, enhanced carrier conductivity, and minimized light scattering.