TY  - JOUR
A1  - Schick, Daniel
A1  - Herzog, Marc
A1  - Wen, Haidan
A1  - Chen, Pice
A1  - Adamo, Carolina
A1  - Gaal, Peter
A1  - Schlom, Darrell G.
A1  - Evans, Paul G.
A1  - Li, Yuelin
A1  - Bargheer, Matias
T1  - Localized excited charge carriers generate ultrafast inhomogeneous strain in the multiferroic BiFeO3
JF  - Physical review letters
N2  - We apply ultrafast x-ray diffraction with femtosecond temporal resolution to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitation. The sound-velocity limited evolution of the observed lattice strains indicates a quasi-instantaneous photoinduced stress which decays on a nanosecond time scale. This stress exhibits an inhomogeneous spatial profile evidenced by the broadening of the Bragg peak. These new data require substantial modification of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain localized to be consistent with the data.
Y1  - 2014
U6  - https://doi.org/10.1103/PhysRevLett.112.097602
SN  - 0031-9007
SN  - 1079-7114
VL  - 112
IS  - 9
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Goldshteyn, Jevgeni
A1  - Bojahr, Andre
A1  - Gaal, Peter
A1  - Schick, Daniel
A1  - Bargheer, Matias
T1  - Selective preparation and detection of phonon polariton wavepackets by stimulated Raman scattering
JF  - Physica status solidi : Physica status solidi
N2  - Wavevector-selective impulsive excitation of phonon-polaritons by a spectrally broad femtosecond transient grating produces wavepackets propagating in opposite directions. The photons in spectrally narrow probe pulses are scattered from these elementary excitations in lithium niobate (LiNbO3). Both elastically and inelastically scattered photons are simultaneously detected in a spectrometer. The Stokes- and anti-Stokes shifted probe pulses uniquely determine the propagation direction of the detected polariton wavepacket components and correspond to creation or annihilation of phonon-polaritons. Our experiments with spectrally broad pump and spectrally narrow probe pulses allows dissecting the four-wave-mixing process into two sequential stimulated Raman scattering events.
Y1  - 2014
U6  - https://doi.org/10.1002/pssb.201350114
SN  - 0370-1972
SN  - 1521-3951
VL  - 251
IS  - 4
SP  - 821
EP  - 828
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Navirian, Hengameh A.
A1  - Schick, Daniel
A1  - Gaal, Peter
A1  - Leitenberger, Wolfram
A1  - Shayduk, Roman
A1  - Bargheer, Matias
T1  - Thermoelastic study of nanolayered structures using time-resolved X-ray diffraction at high repetition rate
JF  - Applied physics letters
N2  - We investigate the thermoelastic response of a nanolayered sample composed of a metallic SrRuO3 electrode sandwiched between a ferroelectric Pb(Zr0.2Ti0.8)O-3 film with negative thermal expansion and a SrTiO3 substrate. SrRuO3 is rapidly heated by fs-laser pulses with 208 kHz repetition rate. Diffraction of X-ray pulses derived from a synchrotron measures the transient out-of-plane lattice constant c of all three materials simultaneously from 120 ps to 5 mu s with a relative accuracy up to Delta c/c = 10(-6). The in-plane propagation of sound is essential for understanding the delayed out-of-plane compression of Pb(Zr0.2Ti0.8)O-3.
Y1  - 2014
U6  - https://doi.org/10.1063/1.4861873
SN  - 0003-6951
SN  - 1077-3118
VL  - 104
IS  - 2
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Gaal, Peter
A1  - Schick, Daniel
A1  - Herzog, Marc
A1  - Bojahr, Andre
A1  - Shayduk, Roman
A1  - Goldshteyn, Jevgeni
A1  - Leitenberger, Wolfram
A1  - Vrejoiu, Ionela
A1  - Khakhulin, Dmitry
A1  - Wulff, Michael
A1  - Bargheer, Matias
T1  - Ultrafast switching of hard X-rays
JF  - Journal of synchrotron radiation
N2  - A new concept for shortening hard X-ray pulses emitted from a third-generation synchrotron source down to few picoseconds is presented. The device, called the PicoSwitch, exploits the dynamics of coherent acoustic phonons in a photo-excited thin film. A characterization of the structure demonstrates switching times of <= 5 ps and a peak reflectivity of similar to 10(-3). The device is tested in a real synchrotron-based pump-probe experiment and reveals features of coherent phonon propagation in a second thin film sample, thus demonstrating the potential to significantly improve the temporal resolution at existing synchrotron facilities.
KW  - ultrafast X-ray diffraction
KW  - thin film
KW  - coherent phonons
KW  - X-ray switching
KW  - pulse shortening
KW  - optical pump X-ray probe
KW  - time-resolved
Y1  - 2014
U6  - https://doi.org/10.1107/S1600577513031949
SN  - 0909-0495
SN  - 1600-5775
VL  - 21
SP  - 380
EP  - 385
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -