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.