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Author: Hänisch, J. × DDC: 530 ×

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Now showing 1 - 4 of 4
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    Pulsed laser deposition of thick BaHfO3-doped YBa 2Cu307-δ films on highly alloyed textured Ni-W tapes
    (Bristol : Institute of Physics Publishing, 2014) Sieger, M.; Hänisch, J.; Iida, K.; Gaitzsch, U.; Rodig, C.; Schultz, L.; Holzapfel, B.; Hühne, R.
    YBa2Cu3O7-δ (YBCO) films with a thickness of up to 3 μm containing nano-sized BaHfO3 (BHO) have been grown on Y2O3/Y-stabilized ZrO2/CeO 2 buffered Ni-9at% W tapes by pulsed laser deposition (PLD). Structural characterization by means of X-ray diffraction confirmed that the YBCO layer grew epitaxial. A superconducting transition temperature T c of about 89 K with a transition width of 1 K was determined, decreasing with increasing BHO content. Critical current density in self-field and at 0.3 T increased with increasing dopant level.
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    Investigation of the strain-sensitive superconducting transition of BaFe1.8Co0.2As2 thin films utilizing piezoelectric substrates
    (Milton Park : Taylor & Francis, 2014) Trommler, S.; Hänisch, J.; Iida, K.; Kurth, F.; Schultz, L.; Holzapfel, B.; Hühne, R.
    The preparation of biaxially textured BaFe1.8Co0.2As2 thin films has been optimized on MgO single crystals and transfered to piezoelectric (001) Pb(Mg1/3Nb2/3)0.72Ti0.28O3 substrates. By utilizing the inverse piezoelectric effect the lattice parameter of these substrates can be controlled applying an electric field, leading to a induction of biaxial strain into the superconducting layer. High electric fields were used to achieve a total strain of up to 0.05% at low temperatures. A sharpening of the resistive transition and a shift of about 0.6 K to higher temperatures was found at a compressive strain of 0.035%.
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    BaFe2As2/Fe bilayers with [001]-tilt grain boundary on MgO and SrTiO3 bicrystal substrates
    (Amsterdam [u.a.] : Elsevier, 2013) Iida, K.; Haindl, S.; Kurth, F.; Hänisch, J.; Schulz, L.; Holzapfel, B.
    Co-doped BaFe2As2 (Ba-122) can be realized on both MgO and SrTiO3 bicrystal substrates with [001]-tilt grain boundary by employing Fe buffer layers. However, an additional spinel (i.e. MgAl 2O4) buffer between Fe and SrTiO3 is necessary since an epitaxial, smooth surface of Fe layer can not be grown on bare SrTiO3. Both types of bicrystal films show good crystalline quality.
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    Tuning functional properties by plastic deformation
    (Milton Park : Taylor & Francis, 2009) Kwon, A.R.; Neu, V.; Matias, V.; Hänisch, J.; Hühne, R.; Freudenberger, J.; Holzapfel, B.; Schultz, L.; Fähler, S.
    It is well known that a variation of lattice constants can strongly influence the functional properties of materials. Lattice constants can be influenced by external forces; however, most experiments are limited to hydrostatic pressure or biaxial stress. Here, we present an experimental approach that imposes a large uniaxial strain on epitaxially grown films in order to tune their functional properties. A substrate made of a ductile metal alloy covered with a biaxially oriented MgO layer is used as a template for growth of epitaxial films. By applying an external plastic strain, we break the symmetry within the substrate plane compared to the as-deposited state. The consequences of 2% plastic strain are examined for an epitaxial hard magnetic Nd2Fe14B film and are found to result in an elliptical distortion of the in-plane anisotropy below the spin-reorientation temperature. Our approach is a versatile method to study the influence of large plastic strain on various materials, as the MgO(001) layer used is a common substrate for epitaxial growth.