@article{HerzogBojahrGoldshteynetal.2012,
  author    = {Herzog, Marc and Bojahr, Andre and Goldshteyn, J. and Leitenberger, Wolfram and Vrejoiu, I. and Khakhulin, D. and Wulff, M. and Shayduk, Roman and Gaal, P. and Bargheer, Matias},
  title     = {Detecting optically synthesized quasi-monochromatic sub-terahertz phonon wavepackets by ultrafast x-ray diffraction},
  series = {Applied physics letters},
  volume    = {100},
  journal   = {Applied physics letters},
  number    = {9},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0003-6951},
  doi       = {10.1063/1.3688492},
  pages     = {4},
  year      = {2012},
  abstract  = {We excite an epitaxial SrRuO3 thin film transducer by a pulse train of ultrashort laser pulses, launching coherent sound waves into the underlying SrTiO3 substrate. Synchrotron-based x-ray diffraction (XRD) data exhibiting separated sidebands to the substrate peak evidence the excitation of a quasi-monochromatic phonon wavepacket with sub-THz central frequency. The frequency and bandwidth of this sound pulse can be controlled by the optical pulse train. We compare the experimental data to combined lattice dynamics and dynamical XRD simulations to verify the coherent phonon dynamics. In addition, we observe a lifetime of 130 ps of such sub-THz phonons in accordance with the theory.},
  language  = {en}
}
@article{ShaydukHerzogBojahretal.2013,
  author    = {Shayduk, Roman and Herzog, Marc and Bojahr, Andre and Schick, Daniel and Gaal, Peter and Leitenberger, Wolfram and Navirian, Hengameh and Sander, Mathias and Goldshteyn, Jevgenij and Vrejoiu, Ionela and Bargheer, Matias},
  title     = {Direct time-domain sampling of subterahertz coherent acoustic phonon spectra in SrTiO3 using ultrafast x-ray diffraction},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {87},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {18},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1098-0121},
  doi       = {10.1103/PhysRevB.87.184301},
  pages     = {7},
  year      = {2013},
  abstract  = {We synthesize sub-THz longitudinal quasimonochromatic acoustic phonons in a SrTiO3 single crystal using a SrRuO3/SrTiO3 superlattice as an optical-acoustic transducer. The generated acoustic phonon spectrum is determined using ultrafast x-ray diffraction. The analysis of the generated phonon spectrum in the time domain reveals a k-vector dependent phonon lifetime. It is observed that even at sub-THz frequencies the phonon lifetime agrees with the 1/omega(2) power law known from Akhiezer's model for hyper sound attenuation. The observed shift of the synthesized spectrum to the higher q is discussed in the framework of nonlinear effects appearing due to the high amplitude of the synthesized phonons.},
  language  = {en}
}
@article{PietschLeitenbergerWendrocketal.2003,
  author    = {Pietsch, Ullrich and Leitenberger, Wolfram and Wendrock, Horst and Bischoff, Lothar and Panzner, Tobias and Grenzer, J{\"o}rg and Pucher, Andreas},
  title     = {Double pinhole diffraction of white synchrotron radiation},
  year      = {2003},
  language  = {en}
}
@article{SendvonKozierowskiPanzneretal.2009,
  author    = {Send, Sebastian and von Kozierowski, Marc and Panzner, Tobias and Gorfman, Semen and Nurdan, Kivanc and Walenta, Albert H. and Pietsch, Ullrich and Leitenberger, Wolfram and Hartmann, Robert and Str{\"u}der, Lothar},
  title     = {Energy-dispersive Laue diffraction by means of a frame-store pnCCD},
  issn      = {0021-8898},
  doi       = {10.1107/S0021889809039867},
  year      = {2009},
  language  = {en}
}
@article{KowarikGerlachLeitenbergeretal.2007,
  author    = {Kowarik, Stefan and Gerlach, Andreas and Leitenberger, Wolfram and Hu J, Witte and W{\"o}ll, Christoph and Schreiber, Frank},
  title     = {Energy-dispersive X-ray reflectivity and GID for real-time growth studies of pentacene thin films},
  issn      = {0040-6090},
  doi       = {10.1016/j.tsf.2006.12.020},
  year      = {2007},
  abstract  = {We use energy-dispersive X-ray reflectivity and grazing incidence diffraction (GID) to follow the growth of the crystalline organic semiconductor pentacene on silicon oxide in-situ and in real-time. The technique allows for monitoring Bragg reflections and measuring X-ray growth oscillations with a time resolution of 1 min in a wide q-range in reciprocal space extending over 0.25-0.80 angstrom(-1), i.e. sampling a large number of Fourier components simultaneously. A quantitative analysis of growth oscillations at several q-points yields the evolution of the surface roughness, showing a marked transition from layer-by-layer growth to strong roughening after four monolayers of pentacene have been deposited. (c) 2006 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@article{KocReinhardtvonReppertetal.2017,
  author    = {Koc, A. and Reinhardt, M. and von Reppert, Alexander and R{\"o}ssle, Matthias and Leitenberger, Wolfram and Gleich, M. and Weinelt, M. and Zamponi, Flavio and Bargheer, Matias},
  title     = {Grueneisen-approach for the experimental determination of transient spin and phonon energies from ultrafast x-ray diffraction data: gadolinium},
  series = {Journal of physics : Condensed matter},
  volume    = {29},
  journal   = {Journal of physics : Condensed matter},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {0953-8984},
  doi       = {10.1088/1361-648X/aa7187},
  pages     = {5884 -- 5891},
  year      = {2017},
  abstract  = {We study gadolinium thin films as a model system for ferromagnets with negative thermal expansion. Ultrashort laser pulses heat up the electronic subsystem and we follow the transient strain via ultrafast x-ray diffraction. In terms of a simple Grueneisen approach, the strain is decomposed into two contributions proportional to the thermal energy of spin and phonon subsystems. Our analysis reveals that upon femtosecond laser excitation, phonons and spins can be driven out of thermal equilibrium for several nanoseconds.},
  language  = {en}
}
@article{ReddyGuptaGomeetal.2009,
  author    = {Reddy, Raghavendra V. and Gupta, Ajay and Gome, Anil and Leitenberger, Wolfram and Pietsch, Ullrich},
  title     = {In situ x-ray reflectivity and grazing incidence x-ray diffraction study of L1(0) ordering in Fe-57/Pt multilayers},
  issn      = {0953-8984},
  doi       = {10.1088/0953-8984/21/18/186002},
  year      = {2009},
  abstract  = {In situ high temperature x-ray reflectivity and grazing incidence x-ray diffraction measurements in the energy dispersive mode are used to study the ordered face-centered tetragonal (fct) L1(0) phase formation in [Fe(19 angstrom)/ Pt(25 angstrom)](x10) multilayers prepared by ion beam sputtering. With the in situ x-ray measurements it is observed that (i) the multilayer structure first transforms to a disordered FePt and subsequently to an ordered fct L1(0) phase, (ii) the ordered fct L1(0) FePt peaks start to appear at 320°C annealing, (iii) the activation energy of the interdiffusion is 0.8 eV and (iv) ordered fct FePt grains have preferential out-of-plane texture. The magneto-optical Kerr effect and conversion electron Mossbauer spectroscopies are used to study the magnetic properties of the as- deposited and 400°C annealed multilayers. The magnetic data for the 400°C annealed sample indicate that the magnetization is at an angle of ~50° from the plane of the film.},
  language  = {en}
}
@article{GuptaGuptaLeitenbergeretal.2012,
  author    = {Gupta, Ranjeeta and Gupta, Ajay and Leitenberger, Wolfram and R{\"u}ffer, R.},
  title     = {Mechanism of stress relaxation in nanocrystalline Fe-N thin films},
  series = {Physical review : B, Condensed matter and materials physics},
  volume    = {85},
  journal   = {Physical review : B, Condensed matter and materials physics},
  number    = {7},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {1098-0121},
  doi       = {10.1103/PhysRevB.85.075401},
  pages     = {7},
  year      = {2012},
  abstract  = {The mechanism of stress relaxation in nanocrystalline Fe-N thin film has been studied. The as-deposited film possesses a strong in-plane compressive stress which relaxes with thermal annealing. Precise diffusion measurements using nuclear resonance reflectivity show that stress relaxation does not involve any long-range diffusion of Fe atoms. Rather, a redistribution of nitrogen atoms at various interstitial sites, as evidenced by conversion electron Mossbauer spectroscopy, is responsible for the relaxation of internal stresses. On the other hand, formation of the. gamma'-Fe4N phase at temperatures above 523 K involves long-range rearrangement of Fe atoms. The activation energy for Fe self-diffusion is found to be 0.38 +/- 0.04 eV.},
  language  = {en}
}
@article{ShaydukNavirianLeitenbergeretal.2011,
  author    = {Shayduk, Roman and Navirian, Hengameh and Leitenberger, Wolfram and Goldshteyn, Jevgenij and Vrejoiu, Ionela and Weinelt, Martin and Gaal, Peter and Herzog, Marc and von Korff Schmising, Clemens and Bargheer, Matias},
  title     = {Nanoscale heat transport studied by high-resolution time-resolved x-ray diffraction},
  series = {New journal of physics : the open-access journal for physics},
  volume    = {13},
  journal   = {New journal of physics : the open-access journal for physics},
  number    = {11},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/13/9/093032},
  pages     = {11},
  year      = {2011},
  abstract  = {We report on synchrotron-based high-repetition rate ultrafast x-ray diffraction (UXRD) experiments monitoring the transport of heat from an epitaxial La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice (SL) into the substrate on timescales from 100 ps to 4 mu s. Transient thermal lattice expansion was determined with an accuracy of 10(-7), corresponding to a sensitivity to temperature changes down to 0.01 K. We follow the heat flow within the SL and into the substrate after the impulsive laser heating leads to a small temperature rise of Delta T = 6 K. The transient lattice temperature can be simulated very well using the bulk heat conductivities. This contradicts the interpretation of previous UXRD measurements, which predicted a long-lasting expansion of SrRuO(3) for more than 200 ps. The disagreement could be resolved by assuming that the heat conductivity changes in the first hundred picoseconds.},
  language  = {en}
}
@article{SchickBojahrHerzogetal.2012,
  author    = {Schick, Daniel and Bojahr, Andre and Herzog, Marc and von Korff Schmising, Clemens and Shayduk, Roman and Leitenberger, Wolfram and Gaa, P. and Bargheer, Matias},
  title     = {Normalization schemes for ultrafast x-ray diffraction using a table-top laser-driven plasma source},
  series = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  volume    = {83},
  journal   = {Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques},
  number    = {2},
  publisher = {American Institute of Physics},
  address   = {Melville},
  issn      = {0034-6748},
  doi       = {10.1063/1.3681254},
  pages     = {7},
  year      = {2012},
  abstract  = {We present an experimental setup of a laser-driven x-ray plasma source for femtosecond x-ray diffraction. Different normalization schemes accounting for x-ray source intensity fluctuations are discussed in detail. We apply these schemes to measure the temporal evolution of Bragg peak intensities of perovskite superlattices after ultrafast laser excitation.},
  language  = {en}
}