Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 25: Focus Session: Resistive Switching by Redox and Phase Change Phenomena II (Valence and phase change in oxides)

DS 25.5: Talk

Wednesday, April 2, 2014, 12:30–12:45, CHE 89

Resistive switching in SrTiO₃:Nb single crystals related to phase transformations — •Christian Rodenbücher, Gustav Bihlmayer, Rainer Waser, and Kristof Szot — Peter-Grünberg-Institut 1 + 7, Forschungszentrum Jülich, 52425 Jülich, Germany

The understanding of the nanoscale origin of resistive switching is of particular importance for the development of non-volatile memories. While investigations of the model material SrTiO₃ using LC-AFM revealed a filamentary type of switching, the switching type changes upon doping with the donor Nb to a cluster-like switching mechanism related to Nb segregation effects in Verneuil-grown single crystals. We show that the switching itself takes place in the surface layer that can change its properties under the influence of external gradients easily. In particular, we demonstrate that during electrodegradation, which can be used as an emulation of switching, fundamental chemical and crystallographic phase transformations from SrTiO₃ towards different substoichiometric TiO_x phases take place in the surface layer under electrical gradients. Based on ab-initio calculations and analyses by various surface-sensitive methods such as XPS, LEED, EBSD and LC-AFM with atomic resolution, we present a potential nanoscale model of the cluster-like resistive switching assuming a phase transformation mechanism inside a nano-filament acting as a switch between the conducting clusters.