Asymmetric transition of electrical resistance in an all-solid-state redox device with Fe₃O₄ and Li-ion electrolyte thin films for physical reservoir computing

In recent years, ion-gating devices have been used in artificial neuromorphic computing and achieved high performance for time-series data processing. However, the origin of this performance still needs to be clarified. In this study, we fabricated an all-solid-state redox device with functional material Fe₃O₄ and Li-ion conducting solid electrolytes, and the transient response of the electrical resistance of the Fe₃O₄ thin film to time-series data input was investigated. The transition between high and low electrical resistance states was asymmetric, and residual Li-ion in the thin film led to a hysteresis effect. These unique features, which are induced by ion-electron dynamics coupling, contributes to the high performance of physical reservoir computing utilizing an ion-gating device.