A novel application of definitive screening design: Co/Cu multilayer thin films

This study aims to determine the optimal deposition parameters to achieve maximum saturation magnetisation of Co/Cu multilayer thin films. A novel statistical approach, Definitive Screening Design was implemented to evaluate the simultaneous effects of five key process variables: Total Thickness, Co deposition rate, Cu deposition rate, Co layer thickness, and Substrate Rotation. A 13-run Definitive Screening Design matrix was utilized for the film deposition, with magnetic characterisation performed via Vibrating Sample Magnetometry. Statistical analysis of the mean response characteristics and contour plots identified Co layer thickness as the most influential factor and the primary driver of interactive effects on the saturation magnetisation response. A regression model was developed to predict the optimal deposition recipe. The optimised conditions were identified as: Total Thickness = 144 nm, Co deposition rate = 0.08 nm/s, Cu deposition rate = 0.6 nm/s, Co layer thickness = 12 nm, and Substrate Rotation = 40 rpm. The regression model predicted a saturation magnetisation value of 1338.2 emu/cm 3 under optimal conditions. Experimental validation confirmed these findings, yielding a saturation magnetisation of 1331.9 emu/cm 3 , representing a 5.48% increase over the initial baseline (1262.7 emu/cm 3 ). Structural characterisation via grazing incidence X-ray diffraction revealed that all synthesized films maintained a face-centered cubic structure with a predominant (111) preferential orientation. Overall, this study establishes Definitive Screening Design as a superior methodology for optimising magnetic multilayer films, providing a streamlined approach to developing next-generation spintronic devices and micro-electromechanical systems. It also presents an application of Definitive Screening Design to optimize magnetic multilayer thin films, demonstrating methodological innovation in experimental materials design. The work makes a valuable methodological contribution to condensed matter physics and materials science.