First principles calculations on electron conduction paths in solid electrolytes: Toward an understanding of the working mechanism of atomic switches

As a first step to clarify the microscopic working mechanism of atomic switches using solid electrolytes, we have examined electronic states and electron transport properties of Ag-Ag ₂S-Ag and Cu-Ta ₂O ₅-Pt systems using standard density functional theory and novel non-equilibrium Green's function method. In both the systems, we found that the bridge structures consisting of excess Ag or Cu in the middle solid electrolyte layer work as electronic conduction paths. In Cu-Ta ₂O ₅-Pt, we also found that O vacancy is much less effective for the enhancement of electronic conduction than excess Cu.