Anomalous time relaxation of the nonvolatile resistive state in bipolar resistive-switching oxide-based memories

Abstract

We have studied long time relaxation effects on the nonvolatile resistance state produced by resistive switching in devices composed by ceramic YBa2Cu3O7−δ and La0.7Sr0.3MnO3/metal (Au, Pt, Ag) interfaces. The time relaxation can be described by a stretched exponential law that is characterized by a power exponent (n) close to 1/2. We found that the characteristic time (τ) increases with increasing temperature and applied power. The origin of the relaxation effect can be related to oxygen diffusion processes, which were recently associated with the mechanism of bipolar switching in complex oxide interfaces. We argue that the anomalous behavior can be understood in terms of diffusion of oxygen ions (or oxygen vacancies) on a two-dimensional surface with a temperature-dependent density of trapping centers, which may correspond, physically, to the diffusion along grain boundaries.