Fig. 6: Electro-resistance model based on electrochemistry.

Schematic representation of the junctions with and without BFO. The oxygen anion (O⁻²; black dots) and oxygen vacancy (V_O ⁺²; hollow dots) distributions are indicated. a OFF state of the 0 nm BFO junctions. The bottom electrode shows a gradual oxygen depletion (and thus depressed superconducting properties) which is very strong near the interface due to the interfacial oxidation (MoSiO_x) of the top MoSi electrode. b By applying V_pol > 0, O⁻² migrate downwards and the oxygen depletion is much more confined near the interface, leaving optimally doped YBCO. This occurs on the junction’s’ edges, where the electric field is stronger. c OFF state of the junctions with BFO, in which YBCO shows gradual oxygen depletion (and thus depressed superconducting properties) which is very strong near the interface. In this state BFO is not significantly oxygen deficient_. d By applying V_pol > 0 (ON state), oxygen vacancies V_O⁺² migrate into de BFO, resulting in a fully oxygenated YBCO and in oxygen-depleted, conducting BFO.