Synaptic and neuronal functionalities on a single oxide film via interface engineering

Achieving both volatile and nonvolatile resistive switching in the same material platform is a key milestone towards the development of dense hardware-based neuromorphic computing. We show that, by suitable choice of electrode metals, a single oxide film can feature both types of behavior. We demonstrate this for two oxides featuring an insulator-to-metal transition: ${\mathrm{Sm}\mathrm{Ni}\mathrm{O}}_{3}$ and ${\mathrm{Nd}\mathrm{Ni}\mathrm{O}}_{3}$. When a current is applied across two-terminal $\mathrm{Pt}$ microdevices, the metal/oxide interface is ohmic and most of the voltage drops horizontally along the oxide film, triggering the transition and inducing volatile resistive switching. However, when $\mathrm{Ti}$ electrodes are used, a ${\mathrm{Ti}\mathrm{O}}_{x}$ layer forms at the metal/oxide interface, across which a strong electric field develops upon application of a current, inducing nonvolatile resistive switching due to vacancy migration. These two electrical behaviors can be observed at the same temperature and coexist at the microscale, leading to different possibilities for implementing neuristors and memristors in the same microcircuit.