Cobalt/copper (Co/Cu) multilayers are prototypical systems for giant magnetoresistance (GMR)-based spintronic devices, where interfacial quality and spin-dependent scattering critically determine performance. In this work, Co/Cu multilayers were fabricated by pulsed laser deposition (PLD) on SITAL ceramics, Si(100), and BK7 substrates, with 10, 20, and 40 bilayer repetitions, in order to elucidate the interplay between microstructure, interfacial diffusion, and magnetotransport properties. Systematic characterization combining atomic force microscopy (AFM), scanning electron microscopy (SEM), SIMS/SNMS depth profiling, vibrating sample magnetometry (VSM), and Hall effect measurements reveals that PLD enables controlled multilayer growth with low background roughness and well-defined periodic structures, despite the presence of characteristic particulates. A clear dependence of the GMR response on both bilayer number and substrate type is observed. Increasing the number of repetitions enhances spin-dependent scattering at Co/Cu interfaces, leading to a progressive increase in the magnetoresistance amplitude, reaching ~−14% for 40-period multilayers on SITAL substrates. This enhancement is attributed to the higher interface density and improved interfacial coherence, as confirmed by SIMS/SNMS analysis showing reduced interdiffusion in thicker stacks. In parallel, Hall effect measurements indicate a reduction in carrier density and an increase in carrier mobility with increasing multilayer thickness, consistent with improved charge transport stability. A pronounced substrate effect is demonstrated: SITAL-supported multilayers exhibit enhanced GMR sensitivity (up to ~44%·T−1) due to increased diffuse spin-dependent scattering at rougher interfaces, whereas Si(100) substrates promote smoother growth, improved structural coherence, and more stable electronic transport. While sputtering typically enables smoother interfaces and higher GMR ratios, PLD offers enhanced flexibility in tailoring interfacial morphology and diffusion processes, which can lead to improved sensitivity under specific conditions. These results establish PLD as a versatile route for tailoring Co/Cu multilayers, enabling controlled optimization of the trade-off between sensitivity and structural quality for advanced spin-valve and magnetic sensor applications.
Constantinescu et al. (Sat,) studied this question.