Electrical and magnetic properties of atomic layer deposited cobalt oxide and iron oxide stacks

Cobalt and iron oxides, due to their tunable structural and magnetic properties, are widely studied for electronic and spintronic applications. However, achieving high coercivity and saturation magnetization in ultrathin films remains a challenge. In this work, we report on the atomic layer deposition (ALD) of nanolaminates and mixed cobalt–iron oxide films on silicon and TiN substrates at 300–450 °C. Using supercycle and multistep ALD methods with ferrocene and cobalt acetylacetonate precursors, we synthesized Co₃O₄–Fe₂O₃ bilayers and ternary ferrites (Co₂FeO₄ and CoFe₂O₄). The structural, morphological, electrical, and magnetic properties were characterized. We observed that thin films (∼7–12 nm) exhibit markedly enhanced breakdown fields and exceptional magnetic coercivity (up to 25 kOe) and saturation magnetization (up to 1000 emu cm⁻³), especially after annealing. These results demonstrate a viable route to engineer ferrite-based thin films with superior magnetic and dielectric performance at nanoscale thicknesses.