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    Observation of strontium segregation in LaAlO3/SrTiO3 and NdGaO3/SrTiO3 oxide heterostructures by X-ray photoemission spectroscopy
    (New York : American Institute of Physics, 2014) Treske, Uwe; Heming, Nadine; Knupfer, Martin; Büchner, Bernd; Koitzsch, Andreas; Di Gennaro, Emiliano; Scotti di Uccio, Umberto; Miletto Granozio, Fabio; Krause, Stefan
    LaAlO3 and NdGaO3 thin films of different thicknesses have been grown by pulsed laser deposition on TiO2-terminated SrTiO3 single crystals and investigated by soft X-ray photoemission spectroscopy. The surface sensitivity of the measurements has been tuned by varying photon energy hν and emission angle Θ. In contrast to the core levels of the other elements, the Sr 3d line shows an unexpected splitting for higher surface sensitivity, signaling the presence of a second strontium component. From our quantitative analysis we conclude that during the growth process Sr atoms diffuse away from the substrate and segregate at the surface of the heterostructure, possibly forming strontium oxide
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    Photoemission electron microscopy of magneto-ionic effects in La0.7Sr0.3MnO3
    (Melville, NY : AIP Publ., 2020) Wilhelm, Marek; Giesen, Margret; Duchoň, Tomáš; Moors, Marco; Mueller, David N.; Hackl, Johanna; Baeumer, Christoph; Hamed, Mai Hussein; Cao, Lei; Zhang, Hengbo; Petracic, Oleg; Glöß, Maria; Cramm, Stefan; Nemšák, Slavomír; Wiemann, Carsten; Dittmann, Regina; Schneider, Claus M.; Müller, Martina
    Magneto-ionic control of magnetism is a promising route toward the realization of non-volatile memory and memristive devices. Magneto-ionic oxides are particularly interesting for this purpose, exhibiting magnetic switching coupled to resistive switching, with the latter emerging as a perturbation of the oxygen vacancy concentration. Here, we report on electric-field-induced magnetic switching in a La0.7Sr0.3MnO3 (LSMO) thin film. Correlating magnetic and chemical information via photoemission electron microscopy, we show that applying a positive voltage perpendicular to the film surface of LSMO results in the change in the valence of the Mn ions accompanied by a metal-to-insulator transition and a loss of magnetic ordering. Importantly, we demonstrate that the voltage amplitude provides granular control of the phenomena, enabling fine-tuning of the surface electronic structure. Our study provides valuable insight into the switching capabilities of LSMO that can be utilized in magneto-ionic devices. © 2020 Author(s).