Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 66: Magnetic Heusler Materials, Semimetals und Oxides
(Joint session of MA and TT organized by MA)
TT 66.3: Vortrag
Donnerstag, 10. März 2016, 10:00–10:15, H34
Introducing magnetic functionality into oxide heterostructures by thermodynamic stabilization: EuO/SrTiO3 — •Patrick Lömker1, Timm Gerber1, Andrei Gloskovskii2, Wolfgang Drube2, and Martina Müller1,3 — 1Forschungszentrum Jülich GmbH, PGI-6, Jülich, Germany — 2DESY Photon Science, DESY, Hamburg, Germany — 3Universität Duisburg-Essen, Duisburg, Germany
In order to introduce magnetic functionality into all-oxide heterostructures, we integrated ultra thin films of the ferromagnetic insulator EuO epitaxially on conducting 0.5% Nb doped SrTiO3(001) (Nb:STO).
We circumvented the use of thick buffer layers (e.g. SrO) to prevent over-oxidation of EuO films by making use of the thermodynamic properties of Eu metal to ultimately form EuO. In particular, in situ XPS shows that Eu-metal only deposition on Nb:STO leads to the formation of ultrathin stoichiometric EuO films through substrate supplied oxygen. Furthermore, the interplay between oxygen pressure, Eu flux and TS is utilized to extended stoichiometric growth to larger film thicknesses. For TS=20∘C we report the formation of fully stoichiometric EuO films, whereas growth at elevated temperature (250-500∘C) yields epitaxial integration with sub-ML interfacial Eu2O3.
Further analysis by LEED, RHEED and XRD reveals the epitaxial relationship EuO(110)/Nb:STO(100). Ex situ magnetic analysis shows bulk-like properties for optimized EuO ultra thin films. Finally, HAXPES experiments were performed at PETRA III confirming the thermodynamical stabilization of ferromagnetic EuO on Nb:STO.