@article{WoernervonKorffSchmisingBargheeretal.2009,
  author    = {Woerner, Michael and von Korff Schmising, Clemens and Bargheer, Matias and Zhavoronkov, Nickolai and Vrejoiu, Ionela and Hesse, Dietrich and Alexe, Marin and Elsaesser, Thomas},
  title     = {Ultrafast structural dynamics of perovskite superlattices},
  issn      = {0947-8396},
  doi       = {10.1007/s00339-009-5174-6},
  year      = {2009},
  abstract  = {Femtosecond x-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO3/PbZr0.2Ti0.8O3 (SRO/ PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1 ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO3 (STO) SL.},
  language  = {en}
}
@article{ZamponiAnsarivonKorffSchmisingetal.2009,
  author    = {Zamponi, Flavio and Ansari, Zunaira and von Korff Schmising, Clemens and Rothhardt, Philip and Zhavoronkov, Nickolai and Woerner, Michael and Elsaesser, Thomas and Bargheer, Matias and Trobitzsch-Ryll, Timo and Haschke, Michael},
  title     = {Femtosecond hard X-ray plasma sources with a kilohertz repetition rate},
  issn      = {0947-8396},
  doi       = {10.1007/s00339-009-5171-9},
  year      = {2009},
  abstract  = {Laser-driven plasma sources of femtosecond hard X-ray pulses have found widespread application in ultrafast X- ray diffraction. The recent development of plasma sources working at kilohertz repetition rates has allowed for diffraction experiments with strongly improved sensitivity, now revealing subtle fully reversible changes of the geometry of crystal lattices. We provide a brief review of this development and present a novel plasma source with an optimized mechanical and optical design, providing a high flux of several 10(10) photons/s at the Cu-K alpha energy of 8.04 keV and a pulse duration of a parts per thousand currency sign300 fs. First experiments, including the generation of Debye-Scherrer diffraction patterns from Si powder, demonstrate the high performance of this source.},
  language  = {en}
}