Artificial synaptic characteristics with strong analog memristive switching in a Pt/CeO₂/Pt structure

Abstract

Artificial synaptic potentiation and depression characteristics were demonstrated with Pt/CeO₂/Pt devices exhibiting polarity-dependent analog memristive switching. The strong and sequential resistance change with its maximum to minimum ratio >10⁵, imperatively essential for stable operation, as repeating voltage application, emulated the potentiation and depression motion of a synapse with variable synaptic weight. The synaptic weight change could be controlled by the amplitude, width, and number of repeated voltage pulses. The voltage polarity-dependent and asymmetric current-voltage characteristics and consequential resistance change are thought to be due to local inhomogeneity of electrical and physical states of CeO₂ such as charging at interface states, valence changes of Ce cations, and so on. These results revealed that the CeO₂ layer could be a promising material for analog memristive switching elements with strong resistance change, as an artificial synapse in neuromorphic systems.