Space charge dynamics in solid electrolytes with steric effect and Vegard stresses: resistive switching and ferroelectric-like hysteresis of electromechanical response

We performed self-consistent modelling of electrotransport and electromechanical response of solid electrolyte thin films allowing for steric effects of mobile charged defects (ions, protons or vacancies), electron degeneration and Vegard stresses. We establish correlations between the features of the space-charge dynamics, current-voltage and bending-voltage curves in the wide frequency range of applied electric voltage. The pronounced ferroelectric-like hysteresis of bending-voltage loops and current maxima on double hysteresis current-voltage loops appear for the electron-open electrodes. The double hysteresis loop with pronounced humps indicates the resistance switching of memristor-type. The switching occurs due to the strong coupling between electronic and ionic subsystem. The sharp meta-stable maximum of the electron density appears near one open electrode and moves to another one during the periodic change of applied voltage. Our results can explain the nature and correlation of electrical and mechanical memory effects in thin films of solid electrolytes. The analytical expression proving that the electrically induced bending of solid electrolyte films can be detected by interferometric methods is derived.