Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity - Poster Session

TT 8.44: Poster

Montag, 26. März 2007, 14:00–17:45, Poster A

Transversal Flux-Transformer Effect in Narrow Superconducting Channels of a-Nb_0.7Ge_0.3 — •F. Otto¹, M. Frisch¹, A. Helzel¹, A. Bilušić¹, D. Babić², C. Sürgers³, and C. Strunk¹ — ¹Inst. for Exp. and Appl. Physics, Univ. Regensburg, Germany — ²Dept. Physics, Univ. Zagreb, Croatia — ³Phys. Inst. and DFG Center for Funct. Nanostr. (CFN), Univ. Karlsruhe, Germany

We study nonlocal vortex transport in mesoscopic amorphous Nb_0.7Ge_0.3 samples. A dc current I is passed through a wire connected via a perpendicular channel, of a length L=2−5 µ m and width w=0.1−2  µ m, with a pair of voltage probes where a nonlocal response V_nl/I is measured. In our low-pinning a-Nb_0.7Ge_0.3, the effect appears in more than half of the superconducting phase diagram, i.e. everywhere where the vortices can be moved easily enough to induce dissipation at very low currents. The maximum of R_nl=V_nl/I for a given temperature occurs at an L-independent magnetic field and is proportional to 1/L. The influence of the vortex-matter viscosity alone is more easily studied in the limit T→ T_c, where pinning effects are negligible. We present a detailed study of the T- and w-dependence of the effect.