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Complex Oxides

Complex oxides exhibit a wealth of phenomena, such as various forms of magnetism, superconductivity, colossal magnetoresistance, and ferroelectricity. The presence of oxygen vacancies can induce large ionic conductivities which enables several applications including solid oxide fuel cells, catalysts, and spintronic devices.

Using in-situ X-ray diffraction the structural phase transition of La0.7Sr0.3MnO3-δ thin films from the ferromagnetic perovskite to the antiferromagnetic brownmillerite structure (see figure) are monitored in real-time during thermal annealing. Polarized neutron reflectometry at the MARIA reflectometer at MLZ in Garching provides a quantitative determination of the oxygen stoichiometry of the film [1]. The topotactic systems SrCoO2.5-3 and La0.6Sr0.4CoO2-5-3 are investigated as well as heterosystems consisting of e.g. a complex oxide film magneto-electrically coupled to a ferroelectric substrate [2], antiferro-/ferromagnetic heterostructures with piezoelectrics, or two different complex oxides and focusing on the proximity effect between them [3].

Magnetite (Fe3O4) constitutes another interesting system which transforms to Maghemite (γ-Fe2O3) by various post-treatments. Presently we study Fe3O4/SrTiO3 and Fe3O4 /PMN-PT thin film heterostructures.

Complex oxides of type La1-xSrxMO3Schematic depiction of the topotactic phase transition between the perovskite and brownmillerite phase found in complex oxides of type La1-xSrxMO3 (M = Mn, Fe, Co).
Copyright: Forschungszentrum Jülich


  1. L. Cao, O. Petracic, P. Zakalek, A.  Weber, U. Rücker, J. Schubert, A. Koutsioubas, S.Mattauch, and Th. Brückel, Reversible Control of Physical Properties via an Oxygen‐Vacancy‐Driven Topotactic Transition in Epitaxial La0.7Sr0.3MnO3−δ Thin Films, Adv. Mater. 31, 1806183 (2019)
  2. M. Schmitz, A. Weber, O. Petracic, M. Waschk, P. Zakalek, S.  Mattauch, A. Koutsioubas, and Th. Brückel, Strain and electric field control of magnetism in La(1--x)SrxMnO3 thin films on ferroelectric BaTiO3 substrates, New J. Phys. 22, 053018 (2020)
  3. M. Waschk, A. Sarkar, J. Barthel, J. Voigt, S. Schröder, P. Zakalek, M. Schmitz, B. J. Kirby, S. Pütter, J. Schubert, and Th. Brückel, Impact of growth kinetics on the interface morphology and magnetization in La1/3 Sr2/3FeO3/La2/3Sr1/3MnO3 heterostructures, J. Phys.: Condens. Matter 32


Oleg Petracic 
Phone: +49 2461 61-4036