Electrodeposition of Co_<i>x</i>Fe_3–<i>x</i>O₄ Epitaxial Films and Superlattices

Spinel ferrites are of interest because of their potential applications in spintronics (spin-based electronics) and solid-state memories. Cobalt ferrite (CoFe₂O₄) is an inverse spinel ferrite. Currently, the utility of CoFe₂O₄ is mainly based on its high coercivity and magnetocrystalline anisotropy. The magnetic and electrical properties of CoFe₂O₄ depend on its Co:Fe ratio. In this paper, a one-step electrodeposition of Co_<i>x</i>Fe_3‑xO₄ (0 < <i>x</i> < 1) thin films from an alkaline Fe³⁺- and Co²⁺-triethanolamine solution is presented. The Co:Fe ratio in the Co_<i>x</i>Fe_3–<i>x</i>O₄ thin films can be tuned by controlling the deposition potential. That is, Co_<i>x</i>Fe_3–<i>x</i>O₄ thin films with tunable chemical and physical properties can be produced from a single solution. Superlattices in the Co_<i>x</i>Fe_3–<i>x</i>O₄ system were also electrodeposited from the same solution by simply pulsing between two potentials. Compared to Co_<i>x</i>Fe_3–<i>x</i>O₄ individual films, superlattices exhibit resistance switching and a more pronounced negative differential resistance (NDR) feature at lower current during perpendicular transport measurements, which could be used in resistive random access memories