Resistive switching and resonant tunneling in epitaxial perovskite tunnel barriers

We report on the relationship between resonant tunneling, resistive switching, and memory phenomena in tunnel junctions with epitaxial SrTiO₃ barriers. Opening and closing of tunneling channels in these barriers are correlated with resonant tunneling from a specific defect that can be eliminated by oxygen annealing. Furthermore, strong coupling of the tunneling electrons with this specific localized state or vibrational mode is responsible for bistable switching, a memory effect, and negative differential resistance. The results impact the interpretation of a wide range of transport phenomena in high-permittivity thin films in metal/insulator/metal structures.