Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 37: Metal Oxide Surfaces II: Structure, Epitaxy and Growth
O 37.4: Vortrag
Dienstag, 2. April 2019, 14:45–15:00, H16
EuO ultrathin films: Growth and strain engineering — •Paul Rosenberger1, Patrick Lömker2, and Martina Müller1,3 — 1Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, Jülich — 2Deutsches Elektronen-Synchrotron (DESY), Hamburg — 3Expt. Physik I, TU Dortmund, Dortmund
It has been shown that the ferromagnetic insulator Europium monoxide (EuO) is a highly efficient spin filter and thus a very interesting material for spintronics. Furthermore, EuO is predicted to become ferroelectric, and thus multiferroic, under sufficiently large biaxial strain. Our goal is to synthesize ultrathin strained EuO films onto suitable substrates and to study their electronic and magnetic properties.
We grow EuO (ultra-)thin films (d 10ML) using MBE in an adsorption-limited growth mode, which is typically employed to synthesize stoichiometric films free from metallic Eu or its higher oxides. We use Yttria-stabilized zirconia, YSZ(001), as a model substrate due to a nearly perfect lattice match. However, we found that for MBE growth of EuO/YSZ thermodynamics has to be considered as oxygen supply from YSZ causes the formation of Eu2O3 or Eu3O4. Based on an XPS study, we present a 4-step growth model of EuO/YSZ(001).
Moreover, we launchend the synthesis of EuO ultrathin films on pseudocubic LaAlO3, LAO(001), which provides 4.2% tensile strain to EuO and is thus a candidate for tailoring a ferroelectric phase in EuO. We varied growth temperature and O2 partial pressure in order to optimize the parameters for strained EuO/LAO and analyzed the resulting films using electron- and X-ray diffraction as well as magnetometry.