Tunnel Electroresistance in Superconducting/Ferroelectric Junctions*

The term tunnel electroresistance (TER) was coined to describe a non-volatile resistive switching observed in ferroelectric tunnel junctions, in which the application of an electric-field pulse drastically changes the electrons’ tunneling rate. This effect can be explained by various mechanisms related to the nonvolatile reversal of the ferroelectric polarization. Using superconducting junctions we demonstrate that the same resistance switching effects can be obtained via an unrelated mechanism: oxygen electro-migration and the resulting modification of the electrodes’ ground-state at the junction interfaces. This mechanism allows simplifying the architecture of the TER-like devices, making unnecessary the presence of a ferroelectric barrier. Furthermore, we demonstrate that in the case of quasiparticles (electrons with superconducting correlations the tunnel resistance switching is over one order-of-magnitude larger than for normal electrons.