Exploring structural, optical, and magnetic analysis of dilute Co incorporated CdS thick films for spintronics

This study involves the preparation using a solid-state reaction method of six thin films of Cd_1-xCo_xS by varying the concentrations of cobalt and cadmium, where x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.1 At. %. The process included mixing Co₂S₃ and CdS powders in stoichiometric ratios, followed by mechanical ball milling, compacting into discs, and analyzing the films' properties. X-ray diffraction (XRD) confirmed the films' crystalline structure and energy-dispersive X-ray spectroscopy (EDX) verified the elemental composition, indicating the successful incorporation of Co into the CdS matrix. X-ray photoelectron spectroscopy (XPS) further detailed the chemical states within the films, showing that Co substitution influenced optical properties. The films' optical transmittance decreased with higher Co content, while reflectance and absorption increased, attributed to Co's impact on the electronic structure. The study also demonstrated a decrease in crystallite size and an increase in lattice strain with rising Co concentration, suggesting a reduction in crystallinity. Optical analyses revealed a decrease in the energy band gap and an increase in refractive index as Co content increased. The refractive index was modeled using the Cauchy equation, and the study noted a corresponding rise in static refractive index and dielectric constant, implying enhanced electromagnetic energy storage capability. Additionally, the magnetic properties showed room-temperature ferromagnetism (RT-FM) across all films, with significant values for saturation magnetization, coercivity, and retentivity.