@article{FeiglPippelPintilieetal.2009,
  author    = {Feigl, Ludwig and Pippel, Eckhard and Pintilie, Lucian and Alexe, Marin and Hesse, Dietrich},
  title     = {Chromium doping of epitaxial PbZr0.2Ti0.8O3 thin films},
  issn      = {0021-8979},
  doi       = {10.1063/1.3141733},
  year      = {2009},
  abstract  = {Epitaxial ferroelectric PbZr0.2Ti0.8O3 thin films were grown by pulsed laser deposition. PbZr0.2Ti0.8O3 was doped with Cr acting as acceptor ion. Microstructural characterization was performed by (high resolution) transmission electron microscopy. The voltage dependence of polarization, dielectric constant, and leakage current were measured with respect to the Cr content. To derive the electronic properties, PZT was considered as a wide-gap semiconductor which allows treating the metal-PZT interface as a Schottky contact. The Cr was found to facilitate the elastic relaxation of the film. Furthermore, the leakage current was increased through a reduction of the Schottky barrier.},
  language  = {en}
}
@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{HerzogLeitenbergerShayduketal.2010,
  author    = {Herzog, Marc and Leitenberger, Wolfram and Shayduk, Roman and van der Veen, Renske Marjan and Milne, Chris J. and Johnson, Steven Lee and Vrejoiu, Ionela and Alexe, Marin and Hesse, Dietrich and Bargheer, Matias},
  title     = {Ultrafast manipulation of hard x-rays by efficient Bragg switches},
  issn      = {0003-6951},
  doi       = {10.1063/1.3402773},
  year      = {2010},
  abstract  = {We experimentally demonstrate efficient switching of the hard x-ray Bragg reflectivity of a SrRuO3 /SrTiO3 superlattice by optical excitation of large-amplitude coherent acoustic superlattice phonons. The rocking curve changes drastically on a 1 ps timescale. The (0 0 116) reflection is almost extinguished (Delta R/R-0=-0.91), while the (0 0 118) reflection increases by more than an order of magnitude (Delta R/R-0=24.1). The change of the x-ray structure factor depends nonlinearly on the phonon amplitude, allowing manipulation of the x-ray response on a timescale considerably shorter than the phonon period. Numerical simulations for a superlattice with slightly changed geometry and realistic parameters predict a switching-contrast ratio Delta R/R-0 of 700 with high reflectivity.},
  language  = {en}
}
@article{KwamenRoessleReinhardtetal.2017,
  author    = {Kwamen, C. and R{\"o}ssle, Matthias and Reinhardt, M. and Leitenberger, Wolfram and Zamponi, Flavio and Alexe, Marin and Bargheer, Matias},
  title     = {Simultaneous dynamic characterization of charge and structural motion during ferroelectric switching},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {96},
  journal   = {Physical review : B, Condensed matter and materials physics},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {2469-9950},
  doi       = {10.1103/PhysRevB.96.134105},
  pages     = {6},
  year      = {2017},
  abstract  = {Monitoring structural changes in ferroelectric thin films during electric field induced polarization switching is important for a full microscopic understanding of the coupled motion of charges, atoms, and domainwalls in ferroelectric nanostructures. We combine standard ferroelectric test sequences of switching and nonswitching electrical pulses with time-resolved x-ray diffraction to investigate the structural response of a nanoscale Pb(Zr0.2Ti0.8)O-3 ferroelectric oxide capacitor upon charging, discharging, and polarization reversal. We observe that a nonlinear piezoelectric response of the ferroelectric layer develops on a much longer time scale than the RC time constant of the device. The complex atomic motion during the ferroelectric polarization reversal starts with a contraction of the lattice, whereas the expansive piezoelectric response sets in after considerable charge flow due to the applied voltage pulses on the electrodes of the capacitor. Our simultaneous measurements on a working device elucidate and visualize the complex interplay of charge flow and structural motion and challenges theoretical modeling.},
  language  = {en}
}
@article{TchoumbaKwamenRoessleLeitenbergeretal.2019,
  author    = {Tchoumba Kwamen, Christelle Larodia and R{\"o}ssle, Matthias and Leitenberger, Wolfram and Alexe, Marin and Bargheer, Matias},
  title     = {Time-resolved X-ray diffraction study of the structural dynamics in an epitaxial ferroelectric thin Pb(Zr0.2Ti0.8)O-3 film induced by sub-coercive fields},
  series = {Applied physics letters},
  volume    = {114},
  journal   = {Applied physics letters},
  number    = {16},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.5084104},
  pages     = {5},
  year      = {2019},
  abstract  = {The electric field-dependence of structural dynamics in a tetragonal ferroelectric lead zirconate titanate thin film is investigated under subcoercive and above-coercive fields using time-resolved X-ray diffraction. The domain nucleation and growth are monitored in real time during the application of an external field to the prepoled thin film capacitor. We propose the observed broadening of the in-plane peak width of the symmetric 002 Bragg reflection as an indicator of the domain disorder and discuss the processes that change the measured peak intensity. Subcoercive field switching results in remnant disordered domain configurations. Published under license by AIP Publishing.},
  language  = {en}
}