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TT: Fachverband Tiefe Temperaturen

TT 15: Superconductivity: Poster Session

TT 15.44: Poster

Tuesday, February 26, 2008, 14:00–18:00, Poster B

Static and time-resolved vortex dynamics in a-Nb_0.7Ge_0.3 — •Florian Otto¹, Martin Frisch¹, Ante Bilušić¹, Dinko Babić², Christoph Sürgers³, and Christoph 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 investigate the motion of vortices in amorphous Nb_0.7Ge_0.3. Because of the very low pinning in this high-κ type-II superconductor, we are able to measure local and non-local transport in the flux-flow regime over large parts of the B-T-phase diagram [1]. Interestingly, there is a finite non-local response close to T_c, even when the applied magnetic field is zero. This points towards the presence of spontaneously formed vortex-antivortex pairs above the Berezinskii-Kosterlitz-Thouless transition. In addition, we report first non-local transport measurements in the time domain, using a boxcar averaging technique.

[1] A.Helzel et al., Phys. Rev. B 74, 220510 (R) (2006)