TY  - JOUR
A1  - Feigl, Ludwig
A1  - Pippel, Eckhard
A1  - Pintilie, Lucian
A1  - Alexe, Marin
A1  - Hesse, Dietrich
T1  - Chromium doping of epitaxial PbZr0.2Ti0.8O3 thin films
N2  - 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.
Y1  - 2009
UR  - http://jap.aip.org/
U6  - https://doi.org/10.1063/1.3141733
SN  - 0021-8979
ER  - 
TY  - JOUR
A1  - Woerner, Michael
A1  - von Korff Schmising, Clemens
A1  - Bargheer, Matias
A1  - Zhavoronkov, Nickolai
A1  - Vrejoiu, Ionela
A1  - Hesse, Dietrich
A1  - Alexe, Marin
A1  - Elsaesser, Thomas
T1  - Ultrafast structural dynamics of perovskite superlattices
N2  - 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.
Y1  - 2009
UR  - http://www.springerlink.com/content/100501
U6  - https://doi.org/10.1007/s00339-009-5174-6
SN  - 0947-8396
ER  - 
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  -