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@PHDTHESIS{Wilbs:824318,
      author       = {Wilbs, Genevieve},
      title        = {{M}agnetic {P}roximity {E}ffects in {N}anoparticle
                      {C}omposite {S}ystems and {M}acrocrystals},
      volume       = {142},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2016-06927},
      isbn         = {978-3-95806-233-7},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {III, 230 S.},
      year         = {2017},
      note         = {RWTH Aachen, Diss., 2017},
      abstract     = {Assemblies of magnetic nanoparticles are of major interest
                      for future applications e.g. in spintronic devices, high
                      density data storage systems or biomedical applications. The
                      reason is not only the obvious miniaturization, but also
                      their novel properties emerging only at the nanoscale.
                      Hence, arranging nanoparticles like atoms in a crystal
                      enables the fabrication of a new class ofmaterials. To gain
                      in-depth understanding of these systems, it is necessary to
                      investigate them on all length scales. The present work
                      provides a novel and extensive contribution to the
                      understanding of the self assembly of iron oxide
                      nanoparticle superstructures and their influence on
                      polarizable matrix materials. Through the investigation of
                      the samples at all stages of preparation, a comprehensive
                      picture of the unique phenomena observed at the end is
                      derived. For this purpose, oleic acid coated iron oxide
                      nanoparticles were deposited on silicon substrates by
                      spincoating to manufacture two-dimensional arrangements.
                      Hereby, the influence of several parameters has been
                      investigated and optimized. Afterwards, the organic
                      surfactant shell was removed by oxygen plasma treatment.
                      This process has been studied in detail, because it
                      initiates a phase transformation that significantly
                      influences the magnetic properties of the system (e.g. by
                      reducing the blocking temperature). Thin palladium or
                      platinum films were then respectively deposited to create a
                      matrix material. Aside from magnetometry measurements, first
                      order reversal curves were obtained in cooperation with the
                      Max-Planck-Institute for Intelligent Systems, both revealing
                      that the matrix materials significantly influence the
                      inter-particle interaction and vice versa. However, only by
                      performing x-ray magnetic circular dichroism experiments at
                      the Advanced Photon Source of the Argonne National
                      Laboratory, it could be evidenced unambiguously thatplatinum
                      can be polarized by an oxide. Additionally, these systems
                      were investigated concerning their electrical transport
                      properties, whereby several nanoparticle phenomena could be
                      observed. Another highlight of this work is the successful
                      preparation of three-dimensional iron oxide nanoparticle
                      assemblies on length scales of > 1000 m by carefully
                      adjusting the parameters of a newly developed centrifuge
                      assisted sedimentation method. Extensive SEM studies
                      combined with magnetometry and sophisticated SAXS
                      experiments resulted in a comprehensive overview on the
                      morphology and magnetism of these so-called
                      ’macrocrystals’, as well as on the nanoparticle
                      arrangement inside them. Like this, highly correlated
                      systems with a macroscopic expansion could be manufactured.
                      Finally, a nanoparticle/palladium multilayer was prepared.
                      It demonstrates that the polarization and magnetoresistance
                      effects found in the two-dimensional systems can only
                      partially be transfered to three dimensional assemblies. In
                      conclusion, this work shows how two- and three-dimensional
                      nanoparticle assemblies can be prepared, how their
                      properties are modified at different stages of preparation
                      and how a polarizable matrixmaterial influences the
                      particles and vice versa.},
      cin          = {JCNS-2 / PGI-4 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-2-20110106 / 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},
      experiment   = {EXP:(DE-MLZ)MARIA-20140101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/824318},
}