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@TECHREPORT{Mennig:890532,
      author       = {Mennig, Julius},
      title        = {{R}eine {S}pinströme in lateralen {S}pinventilen:in
                      $\textit{situ}$ {E}rzeugung und {N}achweis},
      volume       = {18},
      school       = {Universität Köln},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2021-01019},
      isbn         = {978-3-89336-684-2},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / key technologies},
      pages        = {V, 95 S.},
      year         = {2010},
      note         = {Universität Köln, Diss., 2010},
      abstract     = {The subject of this thesis at hand is the generation of
                      pure spin currents in lateral spinvalves.Pure spin currents
                      result from the accumulation of spins and give rise to spin
                      transport in theabsence of charge transport. The diffusive
                      character of spin transport may be the key to
                      prospectiveconcepts for information transmission and
                      processing with significantly reduced dissipation.The
                      investigation of pure spin currents also contributes to a
                      deeper understanding of spin-basedphenomena such as
                      magnetoresistance (e.g. GMR, TMR) and magnetization dynamics
                      (e.g. spintransfertorque STT) by addressing fundamental spin
                      transport and relaxation processes.In order to create a pure
                      spin current, a charge current is injected into a
                      ferromagnet/ nonmagnetinterface. The multi-terminal geometry
                      for local and non-local electrical transport measurementsand
                      the size of the diffusion channel needed for the generation
                      and detection of pure spin currentsrequire a sequence of
                      laterally connected ferromagnetic and nonmagnetic leads on
                      thesubmicron scale, the so called lateral spinvalve. Besides
                      local and non-local electrical transportmeasurements,
                      imaging of the ferromagnetic parts and the diffusion channel
                      by scanning electronmicroscopy with polarization analysis
                      (SEMPA) is employed as an analysis tool. The intent
                      ofapplying SEMPA to the nonmagnetic diffusion channel is to
                      directly image the spin accumulation,which would provide new
                      knowledge about the dynamics, propagation, and relaxation of
                      spincurrents. The small information depth of SEMPA and the
                      crucial importance of clean interfacesand surfaces for the
                      creation of pure spin currents are the motivation to realize
                      the entire samplefabrication and investigation in situ in a
                      complex ultra-high vacuum system.A novel multi-stage
                      fabrication process based on thermal evaporation and
                      structuring with anfocused ion beam system (UHV-FIB) is
                      developed. Thereby, the design of a sample layout givingrise
                      to a single-domain magnetization patterns in the two
                      ferromagnetic leads and allowing forhigh-resolution SEMPA
                      imaging even during the current-induced generation of a pure
                      spin currentturned out to be the major challenge. The
                      development steps to achieving these goals and thederived
                      experience and know-how are presented in detail. An
                      important aspect for interpretingthe non-local transport
                      signal in a spinvalve is the distinct understanding of the
                      remagnetizationprocesses in the nanoscale magnets. This is
                      achieved by a combined analysis of 2-pointmeasurements of
                      the anisotropic magnetoresistance (AMR) effect and SEMPA
                      images of the ferromagnets.For Co/Cu spinvalves the
                      successful detection of pure spin currents is evidenced
                      bycorrelating non-local electrical transport measurements to
                      AMR and SEMPA data. The observedeffect size is in agreement
                      with published work of other groups and indicates the high
                      qualityof the ferromagnet/nonmagnet interfaces in our
                      spinvalves. Imaging of the spin accumulation inthe nonmagnet
                      by SEMPA did not show not the assumed results. Likely
                      reasons as well as otheropen questions are finally
                      discussed.},
      cin          = {PRE-2000 ; Retrocat / IFF-9},
      cid          = {I:(DE-Juel1)PRE2000-20140101 / I:(DE-Juel1)VDB789},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)29},
      url          = {https://juser.fz-juelich.de/record/890532},
}