Abstract

Multicomponent ferrite oxides with mixed valence states and tunable oxygen-defect chemistry are promising active materials for low-power memristive synapses. In this work, Ag/Ni0.3Cu0.2Zn0.5Co0.005Mn0.005Fe1.99O/Ag memristors were fabricated by pulsed laser deposition, and the effects of post-deposition annealing at 700–900 °C on film structure, chemical states, magnetic behavior, resistive switching, and synaptic performance were investigated. The film annealed at 800 °C exhibited a dense surface morphology, improved crystallinity, and uniform elemental distribution. X-ray photoelectron spectroscopy confirmed the coexistence of Fe2+/Fe3+ states and oxygen-related defect components, indicating the presence of oxygen vacancies. Room-temperature magnetic hysteresis measurements revealed ferrite-type magnetic behavior in the annealed films, with the 800-annealed sample showing a relatively well-defined normalized hysteresis response. The optimized device exhibited representative bipolar resistive switching within ±0.5 V, distinguishable high- and low-resistance states, Ohmic conduction in the low-resistance state, and Schottky-emission-dominated transport in the high-resistance state. These results suggest that reversible oxygen-vacancy migration and interfacial barrier modulation govern the switching process. The device showed preliminary synaptic-like transient current responses. Further systematic reliability and conductance-modulation measurements are still required to fully evaluate endurance, reproducibility, and synaptic weight-update behavior. This study demonstrates that annealing-controlled multicomponent ferrite oxides offer a feasible route for energy-efficient memristive synaptic devices.

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