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End date: 2019 × Start date: 2010 × Publisher: Milton Park : Taylor & Francis × search.filters.applied.f.series: New Journal of Physics, Volume 12 ×

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Now showing 1 - 4 of 4
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    The magneto-optical gradient effect in an exchange-biased thin film: Experimental evidence for classical diffraction theory
    (Milton Park : Taylor & Francis, 2010) Schäfer, R.; Hamann, C.; McCord, J.; Schultz, L.; Kamberský, V.
    The magneto-optical gradient effect decorates the boundaries of in-plane domains even at perpendicular incidence of light in an optical polarization microscope. For its explanation, the classical magneto-optical diffraction theory was previously used to derive the effect from the same gyrotropic interaction as the Kerr effect. In order to explain the symmetry of the experimentally observed contrast on bulk ferromagnetic crystals, planar as well as perpendicular subsurface gradients in the magnetization had to be assumed. This was particularly needed when the surface magnetizations in neighboring domains pointed head-on and a gradient contrast appeared also in conditions of vanishing gyrotropic interaction at the surface. The gradient contrast in such conditions should not appear in very thin films where perpendicular magnetization gradients are not enforced by reduction of magnetostatic energy. Here we present the first experimental confirmation of this expectation, thus closing an experimental gap in verifying the predictions of the diffraction theory.
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    Reversible shift in the superconducting transition for La1.85Sr0.15CuO4 and BaFe1.8Co0.2As2 using piezoelectric substrates
    (Milton Park : Taylor & Francis, 2010) Trommler, S.; Hühne, R.; Iida, K.; Pahlke, P.; Haindl, S.; Schultz, L.; Holzapfel, B.
    The use of piezoelectric substrates enables dynamic observation of the strain-dependent properties of functional materials. Based on studies with La1.85Sr0.15CuO4 (LSCO), we extended this approach to the iron arsenic superconductors represented by BaFe2− xCoxAs2 to investigate strain-driven changes in detail. We demonstrate that epitaxial thin films can be prepared on (001) Pb(Mg1/3Nb2/3)0.72Ti0.28O3 substrates using pulsed laser deposition. The structural and electric properties of grown films were characterized in detail. A reversible shift of the superconducting transition of 0.4 K for LSCO and 0.2 K for BaFe1.8Co0.2As2 was observed on applying biaxial strains of 0.022 and 0.017%, respectively.
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    Wide-range strain tunability provided by epitaxial LaAl1−xScxO3 template films
    (Milton Park : Taylor & Francis, 2010) Herklotz, Andreas; Biegalski, Michael D.; Kim, Hyun-Sik; Schultz, Ludwig; Dörr, Kathrin; Christen, Hans M.
    The dielectric diamagnetic LaAl1− xScxO3 (LASO) (x=0–1) is proposed for adjusting of the biaxial in-plane lattice parameter of oxide substrates in the wide range from 3.79 to 4.05 Å (6.5%). This range includes the pseudocubic lattice parameters of most of the currently investigated complex oxides. The in-plane lattice parameter of strain-relaxed LASO films depends linearly on the composition, and these films grow with a smooth surface. On several different LASO-buffered substrates, ferromagnetic La0.7Sr0.3MnO3 (LSMO) films have been grown in predetermined strain states. A series of 30 nm thick LSMO films on LASO-buffered LaSrAlO4(001) demonstrates that continuously controlled coherent strains in a wide range, in this case from − 1 to +0.6%, can be obtained for the functional oxide films grown on LASO.
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    Electronic properties of molecular solids: The peculiar case of solid picene
    (Milton Park : Taylor & Francis, 2010) Roth, Friedrich; Gatti, Matteo; Cudazzo, Pierluigi; Grobosch, Mandy; Mahns, Benjamin; Büchner, Bernd; Rubio, Angel; Knupfer, Martin
    Recently, a new organic superconductor, K-intercalated picene, with high transition temperatures Tc (up to 18 K) has been discovered. We have investigated the electronic properties of an undoped relative of this superconductor, solid picene, using a combination of experimental and theoretical methods. Our results provide deep insights into the occupied and unoccupied electronic states.