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O: Fachverband Oberflächenphysik
O 95: Thin Oxides and Oxide Layers I (joint session DS/HL/O)
O 95.5: Vortrag
Donnerstag, 19. März 2020, 10:30–10:45, CHE 91
Thermal phase transformations through iron oxides/ oxide substrates interfaces — •Mai Hussein Hamed1,2, David N. Mueller1, Tomáš Duchoň1, Ronja Hinz1, Claus M. Schneider1,3, and Martina Müller1,4 — 1Peter-Grünberg-Institut (PGI-6), Forschungszentrum Jülich GmbH, Germany — 2Faculty of Science, Helwan University, Cairo, Egypt — 3Fakultät für Physik, Duisburg-Essen Universität , Germany — 4Experimentelle Physik I, Technische Universität Dortmund, Germany
Oxide heterostructures possess a wide range of electrical and magnetic properties arising, in particular, vie interactions across their interfaces. Therefore, our primary goal is understanding, controlling and tuning the interface properties. In this study, using hard X-ray photoelectron spectroscopy (HAXPES), we demonstrate phase transformations from Fe3O4 to either γ-Fe2O3 or FeO through active redox reactions across three relevant interfaces, i.e. (1) the outside atmosphere/FexOy film interface, (2) the interface between phase-transformed FexOy/FexOy intralayers and (3) the FexOy/oxide substrate interface. We find that the "active" oxide substrates (SrTiO3 or YSZ) play an important role as an additional oxygen supplier or scavenger. This leads to a clear alteration of the standard temperature-pressure phase diagram of iron oxides. Accordingly, we calculate the effective oxygen pressure through the interfaces and adjust the phase diagram. Our findings allow us not only to control the interfaces but more importantly, to tune their physical functionalities by a controlled thermal phase design, giving access to far from equilibrium phases.