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@INPROCEEDINGS{Li:827175,
      author       = {Li, Zi-An and Kovács, András and Tavabi, Amir Hossein and
                      Jin, Chiming and Du, Haifeng and Tian, Mingliang and Farle,
                      Michael and Dunin-Borkowski, Rafal},
      title        = {{M}agnetic {S}kyrmions in an {F}e{G}e {N}anostripe
                      {R}evealed by in situ {E}lectron {H}olography},
      address      = {Weinheim, Germany},
      publisher    = {Wiley-VCH Verlag GmbH $\&$ Co. KGaA},
      reportid     = {FZJ-2017-01373},
      pages        = {974 - 975},
      year         = {2016},
      comment      = {European Microscopy Congress 2016: Proceedings / Li, Zi-An
                      ISBN: 9783527808465},
      booktitle     = {European Microscopy Congress 2016:
                       Proceedings / Li, Zi-An ISBN:
                       9783527808465},
      abstract     = {ntense research interest in magnetic skyrmions is presently
                      driving the development of new fundamental concepts and
                      applications1. Magnetic skyrmions are particle-like,
                      topologically protected swirling spin textures, in which the
                      peripheral spins are oriented vertically, the central spins
                      are oriented in the opposite direction and the intermediate
                      spins rotate smoothly between these two opposite
                      orientations, as shown in the inset to Fig. 1(a). In a range
                      of applied magnetic fields, skyrmion lattices form in
                      certain chiral magnets, such as B20-type magnets, in which a
                      lack of inversion symmetry and spin-orbit coupling gives
                      rise to the Dzyaloshinskii-Moriya interaction. The typical
                      sizes of skyrmions are between 3 and 100 nm. For technically
                      relevant applications, a full understanding of skyrmion
                      formation, stability, manipulation and annihilation is
                      required. Recent experiments have demonstrated the formation
                      of magnetic skyrmion chains in geometrically confined
                      nanostructures2, as shown schematically in Fig. 1(b). A
                      critical step towards real-world device applications
                      involves the development of an approach that can be used to
                      controllably create, manipulate and annihilate skyrmions in
                      magnetic nanostructures, including wire-like
                      geometries.Real-space imaging of complex skyrmion spin
                      configurations using Lorentz microscopy (LM) in the
                      transmission electron microscope (TEM) has enabled the
                      direct observation of skyrmion lattice formation and
                      transformations between different magnetic states with
                      nanometre spatial resolution3. However, the finite size and
                      the inherently weak magnetization of such magnetic
                      nanostructures imposes great experimental challenges for LM.
                      In particular, Fresnel fringe contrast at the specimen edge
                      makes extremely difficult to use LM to obtain magnetic
                      signals in samples that have lateral dimensions of below 10
                      nm. In contrast, off-axis electron holography (EH) in the
                      TEM, which allows electron-optical phase images to be
                      recorded directly with nanometre spatial resolution and high
                      phase sensitivity, provides easier access to magnetic states
                      in nanostructures. Digital acquisition and analysis of
                      electron holograms and sophisticated image analysis software
                      are then essential in studies of weak and slowly varying
                      phase objects such as magnetic skyrmions4.Here, we use both
                      LM and EH to study magnetic skyrmions in a B20-type FeGe
                      nanostripe. The use of liquid nitrogen specimen holder
                      (Gatan model 636) allows the specimen temperature to be
                      varied between 95 and 370 K, and the objective lens of the
                      microscope (FEI Titan 60-300) can be used to apply magnetic
                      fields to the specimen of 0 to 1.5 T. The aim of our study
                      is to resolve the fine magnetic structures of geometrically
                      confined skyrmions and to understand their formation
                      process. Figures 2(a-b) show Lorentz images of a typical
                      FeGe nanostripe, in which a helix to skyrmion transition
                      occurs in response to an applied magnetic field. Figure 2(c)
                      shows a colour-contour composite map derived from a phase
                      image recorded using EH. The slight asymmetry of the
                      contours results from the wedge-shaped specimen thickness
                      profile. Artefacts associated with local changes in specimen
                      thickness in such images can be removed from such images by
                      separating the mean inner potential contribution from the
                      magnetic contribution to the phase, for examples by
                      evaluating the difference between phase images recorded at
                      two different specimen temperatures.},
      month         = {Aug},
      date          = {2016-08-28},
      organization  = {16th European Microscopy Congress (EMC
                       2016), Lyon (France), 28 Aug 2016 - 2
                       Sep 2016},
      cin          = {PGI-5 / ER-C-1},
      cid          = {I:(DE-Juel1)PGI-5-20110106 / I:(DE-Juel1)ER-C-1-20170209},
      pnm          = {143 - Controlling Configuration-Based Phenomena (POF3-143)},
      pid          = {G:(DE-HGF)POF3-143},
      typ          = {PUB:(DE-HGF)8 / PUB:(DE-HGF)7},
      doi          = {10.1002/9783527808465.EMC2016.6263},
      url          = {https://juser.fz-juelich.de/record/827175},
}