@article{vonReppertWilligPudelletal.2018,
  author    = {von Reppert, Alexander and Willig, Lisa and Pudell, Jan-Etienne and Roessle, M. and Leitenberger, Wolfram and Herzog, Marc and Ganss, F. and Hellwig, O. and Bargheer, Matias},
  title     = {Ultrafast laser generated strain in granular and continuous FePt thin films},
  series = {Applied physics letters},
  volume    = {113},
  journal   = {Applied physics letters},
  number    = {12},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.5050234},
  pages     = {5},
  year      = {2018},
  abstract  = {We employ ultrafast X-ray diffraction to compare the lattice dynamics of laser-excited continuous and granular FePt films on MgO (100) substrates. Contrary to recent results on free-standing granular films, we observe in both cases a pronounced and long-lasting out-of-plane expansion. We attribute this discrepancy to the in-plane expansion, which is suppressed by symmetry in continuous films. Granular films on substrates are less constrained and already show a reduced out-of-plane contraction. Via the Poisson effect, out-of-plane contractions drive in-plane expansion and vice versa. Consistently, the granular film exhibits a short-lived out-of-plane contraction driven by ultrafast demagnetization which is followed by a reduced and delayed expansion. From the acoustic reflections of the observed strain waves at the film-substrate interface, we extract a 13\% reduction of the elastic constants in thin 10 nm FePt films compared to bulk-like samples. (C) 2018 Author(s).},
  language  = {en}
}