Dynamic disorder induced memristance in amorphous solids

Motivated by the recent discovery of several amorphous oxides exhibiting remarkable threshold switching and hysteresis in the current-voltage response, we outline a purely quantum mechanism of memristance based on Anderson localization. Concerting first principles methods with molecular dynamic simulations and quantum many-body techniques, we explore the electronic structure of these compounds in the presence of dynamic-ionic disorder. We find that electron localization dominates at the edge of the conduction band, and oxygen deficiency shifts the chemical potential into this localized regime. Experimental observations of sub-breakdown switching behavior arise naturally in this framework as a result of the chemical potential being driven across the transport energy under bias. To model the hysteresis in the current transient, we compute the conductivity with annealed disorder distributions, simulating the migration of oxygen vacancies in a non-equilibrium thermal environment and our results agree with experiment. We therefore resolve amorphous phase oxides to be a great platform for memristors via mobility edge engineering, exposing an avenue for neuromorphic design within the context of well-established defect-engineered semiconductor technologies.