Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 9: Superconductivity - Heterostructures, Andreev Scattering, Proximity Effect, Coexistence

TT 9.3: Vortrag

Montag, 26. März 2007, 16:45–17:00, H20

Superconducting spin valve structures grown on [Fe/V]-(001) superlattices — •Gregor Nowak¹, Kurt Westerholt¹, Moreno Marcellini², Andreas Liebig², Hartmut Zabel¹, and Björgvin Hjörvarsson² — ¹Experimentalphysik /Festkörperphysik, Ruhr - Universität Bochum — ²Department of Physics, University of Uppsala, Sweden

In a superconducting F1/S/F2 epitaxial grown spin valve trilayer structure the superconducting V layer (S) is imbed in to two ferromagnetic Fe layers F1 and F2. Model calculations [1] based on the F/S proximity effect have shown that with suitable parameters for the thicknesses and correlations lengths of the F and S-layers the superconductivity can be switched off and on by rotating the magnetization of F1 and F2 from a parallel to an antiparallel orientation. Experimentally, however, it turned out to be quite difficult to optimize the F1/S/F2 device and until now only very small differences of the superconducting (SC) transition temperature (Tc) between the parallel and antiparallel orientation has been observed [2]. The epitaxial quality of the superconducting V-layer S reduces the impurity and surface scattering of the electrons to an extend that the SC correlation length becomes comparable to the V-film thickness, which is prerequisite for observing a definite SC spin valve effect. We clearly observe the SC spin valve effect with a difference in Tc for the ferromagnetic layers in the parallel or antiparallel orientation of up to 30 mK. References: [1] L. R. Tagirov, Phys. Rev. Lett. , 83, 2058, (1999) [2] J.Y. Gu, C.-Y. You, J. S. Jiang, and S. D. Bader, Phys. Rev. Lett. , 89, 267001, (2002)