TY - JOUR A1 - Schick, Daniel A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Leitenberger, Wolfram A1 - Hertwig, Andreas A1 - Shayduk, Roman A1 - Bargheer, Matias T1 - Ultrafast lattice response of photoexcited thin films studied by X-ray diffraction JF - Structural dynamics N2 - Using ultrafast X-ray diffraction, we study the coherent picosecond lattice dynamics of photoexcited thin films in the two limiting cases, where the photoinduced stress profile decays on a length scale larger and smaller than the film thickness. We solve a unifying analytical model of the strain propagation for acoustic impedance-matched opaque films on a semi-infinite transparent substrate, showing that the lattice dynamics essentially depend on two parameters: One for the spatial profile and one for the amplitude of the strain. We illustrate the results by comparison with high-quality ultrafast X-ray diffraction data of SrRuO3 films on SrTiO3 substrates. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. Y1 - 2014 U6 - https://doi.org/10.1063/1.4901228 SN - 2329-7778 VL - 1 IS - 6 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Schick, Daniel A1 - Bojahr, Andre A1 - Herzog, Marc A1 - von Korff Schmising, Clemens A1 - Shayduk, Roman A1 - Leitenberger, Wolfram A1 - Gaa, P. A1 - Bargheer, Matias T1 - Normalization schemes for ultrafast x-ray diffraction using a table-top laser-driven plasma source JF - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1063/1.3681254 SN - 0034-6748 VL - 83 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Goldshteyn, J. A1 - Leitenberger, Wolfram A1 - Vrejoiu, I. A1 - Khakhulin, D. A1 - Wulff, M. A1 - Shayduk, Roman A1 - Gaal, P. A1 - Bargheer, Matias T1 - Detecting optically synthesized quasi-monochromatic sub-terahertz phonon wavepackets by ultrafast x-ray diffraction JF - Applied physics letters N2 - 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. KW - acoustic waves KW - epitaxial layers KW - phonon dispersion relations KW - terahertz waves KW - thin film devices KW - X-ray diffraction Y1 - 2012 U6 - https://doi.org/10.1063/1.3688492 SN - 0003-6951 VL - 100 IS - 9 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Bojahr, Andre A1 - Schick, Daniel A1 - Märten, Lena A1 - Herzog, Marc A1 - Vrejoiu, Ionela A1 - von Korff Schmising, Clemens A1 - Milne, Chris A1 - Johnson, Steven Lee A1 - Bargheer, Matias T1 - Comparing the oscillation phase in optical pump-probe spectra to ultrafast x-ray diffraction in the metal-dielectric SrRuO3/SrTiO3 superlattice JF - Physical review : B, Condensed matter and materials physics N2 - We measured the ultrafast optical response of metal-dielectric superlattices by broadband all-optical pump-probe spectroscopy. The observed phase of the superlattice mode depends on the probe wavelength, making assignments of the excitation mechanism difficult. Ultrafast x-ray diffraction data reveal the true oscillation phase of the lattice which changes as a function of the excitation fluence. This result is confirmed by the fluence dependence of optical transients. We set up a linear chain model of the lattice dynamics and successfully simulated the broadband optical reflection by unit-cell resolved calculation of the strain-dependent dielectric functions of the constituting materials. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevB.85.224302 SN - 1098-0121 VL - 85 IS - 22 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Bojahr, Andre A1 - Herzog, Marc A1 - Schick, Daniel A1 - Vrejoiu, Ionela A1 - Bargheer, Matias T1 - Calibrated real-time detection of nonlinearly propagating strain waves JF - Physical review : B, Condensed matter and materials physics N2 - Epitaxially grown metallic oxide transducers support the generation of ultrashort strain pulses in SrTiO3 (STO) with high amplitudes up to 0.5%. The strain amplitudes are calibrated by real-time measurements of the lattice deformation using ultrafast x-ray diffraction. We determine the speed at which the strain fronts propagate by broadband picosecond ultrasonics and conclude that, above a strain level of approx. 0.2%, the compressive and tensile strain components travel at considerably different sound velocities, indicating nonlinear wave behavior. Simulations based on an anharmonic linear-chain model are in excellent accord with the experimental findings and show how the spectrum of coherent phonon modes changes with time. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevB.86.144306 SN - 1098-0121 VL - 86 IS - 14 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Gaal, P. A1 - Schick, Daniel A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Shayduk, Roman A1 - Goldshteyn, J. A1 - Navirian, Hengameh A. A1 - Leitenberger, Wolfram A1 - Vrejoiu, Ionela A1 - Khakhulin, D. A1 - Wulff, M. A1 - Bargheer, Matias T1 - Time-domain sampling of x-ray pulses using an ultrafast sample response JF - Applied physics letters N2 - We employ the ultrafast response of a 15.4 nm thin SrRuO3 layer grown epitaxially on a SrTiO3 substrate to perform time-domain sampling of an x-ray pulse emitted from a synchrotron storage ring. Excitation of the sample with an ultrashort laser pulse triggers coherent expansion and compression waves in the thin layer, which turn the diffraction efficiency on and off at a fixed Bragg angle during 5 ps. This is significantly shorter than the duration of the synchrotron x-ray pulse of 100 ps. Cross-correlation measurements of the ultrafast sample response and the synchrotron x-ray pulse allow to reconstruct the x-ray pulse shape. Y1 - 2012 U6 - https://doi.org/10.1063/1.4769828 SN - 0003-6951 VL - 101 IS - 24 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Schick, Daniel A1 - Bojahr, Andre A1 - Herzog, Marc A1 - Gaal, P. A1 - Vrejoiu, I. A1 - Bargheer, Matias T1 - Following Strain-Induced Mosaicity Changes of Ferroelectric Thin Films by Ultrafast Reciprocal Space Mapping JF - Physical review letters N2 - We investigate coherent phonon propagation in a thin film of ferroelectric PbZr0.2Ti0.8O3 (PZT) by ultrafast x-ray diffraction experiments, which are analyzed as time-resolved reciprocal space mapping in order to observe the in-and out-of-plane structural dynamics, simultaneously. The mosaic structure of the PZT leads to a coupling of the excited out-of-plane expansion to in-plane lattice dynamics on a picosecond time scale, which is not observed for out-of-plane compression. Y1 - 2013 U6 - https://doi.org/10.1103/PhysRevLett.110.095502 SN - 0031-9007 SN - 1079-7114 VL - 110 IS - 9 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Shayduk, Roman A1 - Herzog, Marc A1 - Bojahr, Andre A1 - Schick, Daniel A1 - Gaal, Peter A1 - Leitenberger, Wolfram A1 - Navirian, Hengameh A1 - Sander, Mathias A1 - Goldshteyn, Jevgenij A1 - Vrejoiu, Ionela A1 - Bargheer, Matias T1 - Direct time-domain sampling of subterahertz coherent acoustic phonon spectra in SrTiO3 using ultrafast x-ray diffraction JF - Physical review : B, Condensed matter and materials physics N2 - 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. Y1 - 2013 U6 - https://doi.org/10.1103/PhysRevB.87.184301 SN - 1098-0121 VL - 87 IS - 18 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Bojahr, Andre A1 - Herzog, Marc A1 - Mitzscherling, Steffen A1 - Maerten, Lena A1 - Schick, Daniel A1 - Goldshteyn, J. A1 - Leitenberger, Wolfram A1 - Shayduk, R. A1 - Gaal, P. A1 - Bargheer, Matias T1 - Brillouin scattering of visible and hard X-ray photons from optically synthesized phonon wavepackets JF - Optics express : the international electronic journal of optics N2 - We monitor how destructive interference of undesired phonon frequency components shapes a quasi-monochromatic hypersound wavepacket spectrum during its local real-time preparation by a nanometric transducer and follow the subsequent decay by nonlinear coupling. We prove each frequency component of an optical supercontinuum probe to be sensitive to one particular phonon wavevector in bulk material and cross-check this by ultrafast x-ray diffraction experiments with direct access to the lattice dynamics. Establishing reliable experimental techniques with direct access to the transient spectrum of the excitation is crucial for the interpretation in strongly nonlinear regimes, such as soliton formation. Y1 - 2013 U6 - https://doi.org/10.1364/OE.21.021188 SN - 1094-4087 VL - 21 IS - 18 SP - 21188 EP - 21197 PB - Optical Society of America CY - Washington ER - TY - GEN A1 - Pavlenko, Elena S. A1 - Sander, Mathias A1 - Mitzscherling, Steffen A1 - Pudell, Jan-Etienne A1 - Zamponi, Flavio A1 - Rössle, Matthias A1 - Bojahr, Andre A1 - Bargheer, Matias T1 - Azobenzene – functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers N2 - We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain ε ∼ 5 × 10−4 is calibrated by ultrafast X-ray diffraction. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 297 Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-101996 VL - 8 SP - 13297 EP - 13302 ER -