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@PHDTHESIS{Khan:845370,
      author       = {Khan, Muhammad Imtiaz},
      title        = {{C}urrent-{I}nduced {M}agnetization {D}ynamics in
                      {F}erromagnetic {N}anowires},
      volume       = {166},
      school       = {Universität Duisburg},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2018-02644},
      isbn         = {978-3-95806-308-2},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {VI, 138 S.},
      year         = {2018},
      note         = {Universität Duisburg, Diss., 2017},
      abstract     = {This thesis deals with the magnetization dynamics in
                      nanostructures of NiFe alloys (Ni$_{80}$Fe$_{20}$ and
                      Ni$_{20}$Fe$_{80}$) induced by an electric current via the
                      spin transfer torque effect (STT). Single-pulse and
                      time-resolved experiments have been carried out, imaging the
                      magnetic domains in a photoemission electron
                      microscope(PEEM), using the circular polarized synchrotron
                      radiation of BESSY-II. In single-pulse experiments, the
                      reaction of magnetic domains and domain walls(DWs) upon
                      individual current pulses in the nanostructures are studied
                      and the approximate threshold current density for the DW
                      motion was determined to about 7.5 x 10$^{11}$ A/m$^{2}$. We
                      designed three different types of nanostructures, favorable
                      for different types of DWs: a V-shape, a half ring-shape and
                      a notched half ring- shape. Besides the influence of the
                      current pulses on domain textures, we observed that high
                      current pulses created new multiple domain configurations,
                      like diamond patterns and domain arrays. For those, rather
                      than nucleation due to STT, a temperature rise seems to be
                      the dominant mechanism. We also observed the conversion from
                      a vortex-like flux closure domain into a transverse wall
                      (TW). In order to enable time-resolved studies of the DW
                      motion in pump-probe experiment swith sufficient intensity,
                      several modifications for a time-resolving mode had to be
                      integrated into our energy filtered aberration-corrected
                      PEEM:(1) A new modified sample holder for shorter current
                      pulses ( $\thicksim$ 1 ns). (2) A negative deflection-gating
                      concept to increase the intensity while discriminating the
                      signal from all the multi-bunches (MBs) with no adjacent
                      pump pulse. Finally, we performed a pump-probe experiment
                      and have observed the dynamics of small reversible DW
                      boundary changes on a ns timescale for the first time in a
                      truly current-induced pump-probe experiment.},
      cin          = {PGI-6},
      cid          = {I:(DE-Juel1)PGI-6-20110106},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/845370},
}