Nanoscale resistive switching in SrTiO3 thin films

The local conductivity of SrTiO3 thin films epitaxially grown on SrRuO3-buffered SrTiO3 single crystals has been investigated in detail with an atomic force microscope equipped with a conducting tip (LC-AFM). These experiments demonstrate that the conductivity of SrTiO3 thin films originates from nanoscale well-conducting filaments connecting the surface to the SrRuO3 bottom electrode. The electrical conduction of the filaments is shown to be reversible modulated over several orders of magnitude by application of an appropriate electrical field. We analyze the resistive switching by addressing individual filaments with the AFM tip as well as by scanning areas up to the mu m scale. Temperature dependent measurements reveal that resistive switching on a macroscopic scale can be traced down to the insulator-to-metal transition of the independently switchable filaments.