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DDC: 530 × Subject: Superconducting transitions ×

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    Superconducting switching due to a triplet component in the Pb/Cu/Ni/Cu/Co2Cr1-xFexAly spin-valve structure
    (Frankfurt am Main : Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2019) Kamashev, A.A.; Garif'yanov, N.N.; Validov, A.A.; Schumann, J.; Kataev, V.; Büchner, B.; Fominov, Y.V.; Garifullin, I.A.
    We report the superconducting properties of the Co2Cr1-xFexAly/Cu/Ni/Cu/Pb spin-valve structure the magnetic part of which comprises the Heusler alloy layer HA = Co2Cr1-xFexAly with a high degree of spin polarization (DSP) of the conduction band and a Ni layer of variable thickness. The separation between the superconducting transition curves measured for the parallel (α = 0°) and perpendicular (α = 90°) orientation of the magnetization of the HA and the Ni layers reaches up to 0.5 K (α is the angle between the magnetization of two ferromagnetic layers). For all studied samples the dependence of the superconducting transition temperature Tc on α demonstrates a deep minimum in the vicinity of the perpendicular configuration of the magnetizations. This suggests that the observed minimum and the corresponding full switching effect of the spin valve is caused by the long-range triplet component of the superconducting condensate in the multilayer. Such a large effect can be attributed to a half-metallic nature of the HA layer, which in the orthogonal configuration efficiently draws off the spin-polarized Cooper pairs from the space between the HA and Ni layers. Our results indicate a significant potential of the concept of a superconducting spin-valve multilayer comprising a half-metallic ferromagnet, recently proposed by A. Singh et al., Phys. Rev. X 2015, 5, 021019, in achieving large values of the switching effect.
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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.