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- ItemRolled-up tubes and cantilevers by releasing SrRuO 3-Pr 0.7Ca 0.3MnO 3 nanomembranes(New York, NY [u.a.] : Springer, 2011) Deneke, C.; Wild, E.; Boldyreva, K.; Baunack, S.; Cendula, P.; Mönch, I.; Simon, M.; Malachias, A.; Dörr, K.; Schmidt, O.G.Three-dimensional micro-objects are fabricated by the controlled release of inherently strained SrRuO 3/Pr 0.7Ca 0.3MnO 3/SrRuO 3 nanometer-sized trilayers from SrTiO 3 (001) substrates. Freestanding cantilevers and rolled-up microtubes with a diameter of 6 to 8 μm are demonstrated. The etching behavior of the SrRuO3 film is investigated, and a selectivity of 1:9,100 with respect to the SrTiO3 substrate is found. The initial and final strain states of the rolled-up oxide layers are studied by X-ray diffraction on an ensemble of tubes. Relaxation of the sandwiched Pr0.7Ca0.3MnO3 layer towards its bulk lattice parameter is observed as the major driving force for the roll-up of the trilayers. Finally, μ-diffraction experiments reveal that a single object can represent the ensemble proving a good homogeneity of the rolled-up tubes.
- ItemStrain-controlled switching kinetics of epitaxial PbZr0.52Ti0.48O3 films(Milton Park : Taylor & Francis, 2013) Herklotz, A.; Guo, E.-J.; Biegalski, M.D.; Christen, H.-M.; Schultz, L.; Dörr, K.We investigate the effect of biaxial strain on the switching of ferroelectric thin films. The strain state of epitaxial PbZr0.52Ti0.48O3 films is controlled directly and reversibly by the use of piezoelectric Pb(Mg1/3Nb2/3)0.72Ti0.28O3 (001) substrates. At small external electric fields, the films show switching characteristics consistent with a creep-like domain wall motion. In this regime, we find a huge decrease of the switching time under compressive strain. For larger external electric fields, the domain wall motion is in a depinning regime. The effect of compressive strain is more moderate in this region and shows a reduction in the switching kinetics.