Berlin 2008 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 5: Spindependent Transportphenomena I

MA 5.2: Vortrag

Montag, 25. Februar 2008, 10:30–10:45, H 0112

Influence of spin-orientation on Tc in superconducting spin-valves CoFeHf/Nb/CoFeHf — •Yuansu Luo and Konrad Samwer — I. physikalisches Institut, Universität Göttingen, Friedrich-Hund Platz 1, 37077 Göttingen

Spin-valve-like structures CoFeHf/Nb/CoFeHf were investigated to show a potential influence of the spin orientation on superconducting transition temperature Tc of the space layer Nb, where the alloy of CoFeHf with 25at.%Hf was chosen as magnetic layers due to its amorphous and soft magnetic properties, having a high resistivity and a low saturation magnetization which may effectively diminish the proximity effect. The layer thicknesses used are 2-6nm for CoFeHf and 15nm for Nb, i.e. less than the coherence length. The upper magnetic layer deposited at room temperature exhibits a coercive field of a few Oe, which is smaller than that of the bottom magnetic layer prepared at 300°C and pinned additionally by a hard magnetic layer of CoFe(2nm). Transport measurements were carried out at low temperatures with an electric current and a magnetic field both in plan. The critical temperature Tc was measured to be 5.40K for the multilayered samples. It slightly shifts upwards about 25mK when changing the spin configuration of two magnetic layers from parallel to antiparallel. The small superconducting spin-valve effect might be related to strongly enhanced critical magnetic field. (Supported by DFG-Leibniz program)