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@PHDTHESIS{Callsen:186705,
      author       = {Callsen, Martin},
      title        = {{A}b initio investigations of π-conjugated-molecule-metal
                      interfaces for molecular electronics and spintronics},
      volume       = {92},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2015-00777},
      isbn         = {978-3-89336-992-8},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {VIII, 155 S.},
      year         = {2014},
      note         = {RWTH Aachen, Diss., 2013},
      abstract     = {The demand for continuous miniaturization of electronic
                      devices poses an enormous challenge to conventional
                      electronics. Instead of further miniaturizing the already
                      established silicon based technology beyond the nanoscale,
                      designing electronic devices by the bottom-up strategy is a
                      promising alternative. As the currently smallest imaginable
                      parts for electronic devices, single atoms or molecules
                      adsorbed on a substrate are the subject of research in the
                      field of molecular electronics. In addition molecular
                      spintronics is a quickly rising field, which promises
                      advantages over electronics like a lower power consumption.
                      In spintronics the charge current is replaced by a spin
                      current. Both molecular electronics and molecular
                      spintronics require a proper theoretical description to
                      design new materials and to propose candidates for future
                      devices. Density functional theory is the method of choice
                      to efficiently describe the molecule surface interfaces
                      under consideration. For a realistic description of the
                      system a suitable approximation for the exchange correlation
                      functional has to be made. In particular for weakly bound
                      organic molecules adsorbed on surfaces common approximations
                      to the exchange correlation functional fail to correctly
                      account for van der Waals interactions, which are in this
                      case the dominant contribution to the binding. To find a
                      correction for this deficiency is still subject of current
                      research. In this thesis we investigate molecule surface
                      systems of small $\pi$ conjugated molecules adsorbed on
                      metal surfaces. For thiophene on Cu(111) we find weak
                      chemisorption as binding mechanism while cyclooctatetraene
                      is physisorbed on Au(111) and chemisorbed on the metal (100)
                      surfaces of Au, Ag and Cu. In all these regimes of binding
                      strength we asses semi-empirical and $\textit{ab initio}$
                      approaches to correct for vdWinteractions in DFT. Based on
                      the insights gained about the organic metal interfaces for
                      different molecule surface interaction strengths, we propose
                      two promising magnetic systems for molecular spintronics
                      applications. Cyclooctatetraene adsorbed on magnetic
                      transition metal adatoms on Au(111) shows sharp spin split
                      molecular orbital like features, which are characteristic
                      for a spin filter. Paracyclophane adsorbed on the
                      ferromagnetic Fe/W(110) surface and the antiferromagnetic
                      Fe/W(100) surface in addition to the spin filter
                      characteristics is an example for the modification of the
                      magnetic properties of a surface by the adsorption of
                      organic molecules. In particular the exchange coupling
                      strength between the Fe atoms directly interacting with the
                      molecule is increased, which leads to higher coercivity
                      fields and Curie temperatures of the sample.},
      keywords     = {Dissertation (GND)},
      cin          = {PGI-1 / IAS-1},
      cid          = {I:(DE-Juel1)PGI-1-20110106 / I:(DE-Juel1)IAS-1-20090406},
      pnm          = {422 - Spin-based and quantum information (POF2-422)},
      pid          = {G:(DE-HGF)POF2-422},
      typ          = {PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/186705},
}