Influence of thickness and annealing temperature on surface roughness and functional properties of Co80Ce20 thin films on polymer substrates

This study investigates the impact of annealing conditions and thickness on the properties of Co₈₀Ce₂₀ thin films deposited on flexible polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA) substrates. Atomic force microscopy (AFM) analysis reveals that surface roughness increases with temperature, rising from 2.90 nm to 3.28 nm for PET and from 2.44 nm to 2.67 nm for PMMA. Conversely, increasing thickness reduces roughness, from 6.21 nm to 3.28 nm for PET and from 9.36 nm to 2.67 nm for PMMA. Surface energy decreases with thickness, correlating with enhanced hydrophobicity. Hardness peaks at 4.69 GPa for PET at 120 °C and 3.20 GPa for PMMA at 80 °C, while Young's modulus reaches 16.96 GPa for PET and 16.03 GPa for PMMA. Optical transmittance diminishes with thickness, with maximum values of 16.46 % for PET and 16.55 % for PMMA at 10 nm, decreasing to 0.13 % at 50 nm. Electrical measurements show reduced sheet resistance and increased conductivity, with the lowest resistivity at 1.37 × 10⁻⁴ Ω•cm. Magnetic measurements indicate saturation magnetization peaks at 80 °C for PET and 60 °C for PMMA, with increased surface roughness leading to reduce coercivity (Hc). These findings highlight the tunable properties of Co80Ce20 thin films for flexible electronics and magnetic storage applications.