Direct observation of a repeatable change in electronic states with applied electric voltage pulses in the metal-insulator-metal structure

By the microspectroscopic imaging of optical reflectivity for the La1-xSrxFeO3-delta thin film with indium-tin-oxide electrodes, we observed that the shape of the conducting area between two electrodes is reversibly varied with applied electric voltage pulses and that causes a repeatable change in the electrical resistance between the electrodes. These results can be explained by the oxygen-ion migration with applied electric field, which induces a variation in the distribution of the Fe4+ ions in the thin film.