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@INPROCEEDINGS{Hussein:888151,
      author       = {Hussein, Mai and Müller, Martina and Mueller, David N. and
                      Petracic, Oleg and Elnaggar, Hebatalla and Brückel, Thomas},
      title        = {{THERMAL} {CONTROL} {OF} {MAGNETIC} {PHASE}
                      {TRANSFORMATIONS} {THROUGH} {ACTIVE} {INTERFACES}},
      reportid     = {FZJ-2020-04725},
      year         = {2020},
      abstract     = {Oxide heterostructures possess a wide range of electrical
                      and magnetic properties arising, in particular, via
                      interactions across their interfaces. Iron oxides generally
                      and Fe3O4 particularly have a multitude of electric and
                      magnetic functionalities which makes them interesting
                      candidates for magnetic applications and heterogeneous
                      catalysis. Controlling the oxide-interfaces opens additional
                      manufacturing possibilities for functional devices.
                      Moreover, switching between the different functional phases
                      of iron oxides may open up novel routes to control and tune
                      magnetic states via thermal phase design. It is therefore,
                      our primary goal to understand, control, and tune the
                      interface properties of Fe3O4/SrTiO3 and Fe3O4/YSZ
                      heterostructures. 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.
                      Moreover, using X-ray absorption spectroscopy (XAS) and
                      X-ray magnetic circular and linear dichroism (XMCD and
                      XMLD), we monitor the local distortion and the orbital
                      character of the Fe sites in the iron oxides thin films. 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.},
      month         = {Dec},
      date          = {2020-12-07},
      organization  = {Joint European Magnetic Symposia 2020
                       Virtual Conference, Abreu Events,
                       Lisbon Office (Portugal), 7 Dec 2020 -
                       11 Dec 2020},
      subtyp        = {Invited},
      cin          = {JCNS-2 / PGI-6 / PGI-4 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)PGI-6-20110106 /
                      I:(DE-Juel1)PGI-4-20110106 / $I:(DE-82)080009_20140620$},
      pnm          = {144 - Controlling Collective States (POF3-144) / 524 -
                      Controlling Collective States (POF3-524) / 6212 - Quantum
                      Condensed Matter: Magnetism, Superconductivity (POF3-621) /
                      6213 - Materials and Processes for Energy and Transport
                      Technologies (POF3-621) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (POF3-623)},
      pid          = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-524 /
                      G:(DE-HGF)POF3-6212 / G:(DE-HGF)POF3-6213 /
                      G:(DE-HGF)POF3-6G4},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/888151},
}