TY  - JOUR
A1  - Herzog, Marc
A1  - Leitenberger, Wolfram
A1  - Shayduk, Roman
A1  - van der Veen, Renske Marjan
A1  - Milne, Chris J.
A1  - Johnson, Steven Lee
A1  - Vrejoiu, Ionela
A1  - Alexe, Marin
A1  - Hesse, Dietrich
A1  - Bargheer, Matias
T1  - Ultrafast manipulation of hard x-rays by efficient Bragg switches
N2  - 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.
Y1  - 2010
UR  - http://apl.aip.org/
U6  - https://doi.org/10.1063/1.3402773
SN  - 0003-6951
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  - Herzog, Marc
A1  - Schick, Daniel
A1  - Leitenberger, Wolfram
A1  - Shayduk, Roman
A1  - van der Veen, Renske M.
A1  - Milne, Christopher J.
A1  - Johnson, Steven Lee
A1  - Vrejoiu, Ionela
A1  - Bargheer, Matias
T1  - Tailoring interference and nonlinear manipulation of femtosecond x-rays
JF  - New journal of physics : the open-access journal for physics
N2  - We present ultrafast x-ray diffraction (UXRD) experiments on different photoexcited oxide superlattices. All data are successfully simulated by dynamical x-ray diffraction calculations based on a microscopic model, that accounts for the linear response of phonons to the excitation laser pulse. Some Bragg reflections display a highly nonlinear strain dependence. The origin of linear and two distinct nonlinear response phenomena is discussed in a conceptually simpler model using the interference of envelope functions that describe the diffraction efficiency of the average constituent nanolayers. The combination of both models facilitates rapid and accurate simulations of UXRD experiments.
Y1  - 2012
U6  - https://doi.org/10.1088/1367-2630/14/1/013004
SN  - 1367-2630
VL  - 14
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -