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Author: Frömter, Robert × Type: Article ×

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    Enabling time-resolved 2D spatial-coherence measurements using the Fourier-analysis method with an integrated curved-grating beam monitor
    (Washington, DC : Soc., 2020) Bagschik, Kai; Schneider, Michael; Wagner, Jochen; Buss, Ralph; Riepp, Matthias; Philippi-Kobs, Andre; Müller, Leonard; Roseker, Wojciech; Trinter, Florian; Hoesch, Moritz; Viefhaus, Jens; Eisebitt, Stefan; Grübel, Gerhard; Oepen, Hans Peter; Frömter, Robert
    Direct 2D spatial-coherence measurements are increasingly gaining importance at synchrotron beamlines, especially due to present and future upgrades of synchrotron facilities to diffraction-limited storage rings. We present a method to determine the 2D spatial coherence of synchrotron radiation in a direct and particularly simple way by using the Fourier-analysis method in conjunction with curved gratings. Direct photon-beam monitoring provided by a curved grating circumvents the otherwise necessary separate determination of the illuminating intensity distribution required for the Fourier-analysis method. Hence, combining these two methods allows for time-resolved spatial-coherence measurements. As a consequence, spatial-coherence degradation effects caused by beamline optics vibrations, which is one of the key issues of state-of-the-art X-ray imaging and scattering beamlines, can be identified and analyzed. © 2020 Optical Society of America.
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    Micromagnetic investigation of domain and domain wall evolution through the spin-reorientation transition of an epitaxial NdCo5 film
    ([London] : IOP, 2017-3-1) Seifert, Marietta; Schultz, Ludwig; Schäfer, Rudolf; Hankemeier, Sebastian; Frömter, Robert; Oepen, Hans Peter; Neu, Volker
    The domain pattern and the domain wall microstructure throughout the spin-reorientation transition of an epitaxial NdCo5 thin film are investigated by micromagnetic simulations. The temperature-dependent anisotropy constants K1 and K2, which define the anisotropy energy term in the model, are chosen to reflect the easy axis—easy cone—easy plane spin-reorientation transition observed in epitaxial NdCo5 thin films. Starting at the high-temperature easy c-axis regime, the anisotropy constants are changed systematically corresponding to a lowering of the temperature of the system. The character of the domain walls and their profiles are analysed. The calculated domain configurations are compared to the experimentally observed temperature-dependent domain structure of an in-plane textured NdCo5 thin film.