Microscopic Mechanisms of Local Interfacial Resistive Switching in LaMnO_3+δ

High Resolution Image Download MS PowerPoint Slide Manganite perovskites exhibit promising resistive switching properties, for which the understanding of the related microscopic physicochemical changes taking place is still rather scarce. In this work the resistance of a LaMnO 3+δ thin film has been locally tuned within a range of 2 orders of magnitude using conductive atomic force microscopy. With the use of X-ray photoemission electron microscopy it has been possible to simultaneously unravel composition and work function modification related to changes in the LaMnO 3+δ resistance state. The resistance change is found to be triggered by oxygen ions drifting to the surface, where they remain adsorbed. Concomitant to this oxygen displacement, the Mn oxidation state is reduced from +3.6 to +3.1, while the work function decreases by 0.28 eV. We discuss the effect of these physicochemical modifications on the conduction mechanism, which is in agreement with a space-charge-limited conduction (SCLC) mechanism where the current is restrained by the density of traps at the interface. We show that the resistive switching in the material can be described as a change of the transport regime from a trap-free to a trap-controlled SCLC, depending on the oxygen content in the material.