Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 10: Superconductivity - Tunneling, Josephson Junctions, SQUIDs

TT 10.10: Vortrag

Samstag, 5. März 2005, 10:45–11:00, TU H104

Experiments with Josephson vortex ratchets — •Edward Goldobin¹, Markus Beck¹, Dieter Koelle¹, Reinhold Kleiner¹ und Michael Siegel² — ¹Physikalische Institut – Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen — ²Institut für Mikro- und Nanoelektronische Systeme, Universität Karlsruhe, Hertzstr. 16, 76187 Karlsruhe

We investigate experimentally a Josephson vortex ratchet — a fluxon in an asymmetric periodic potential driven by a force with zero time average. The highly asymmetric periodic potential is created in underdamped annular long Josephson junction by means of a current injector[1]. Experimental characterization shows good asymmetry of the constructed potential. We have measured the ratchet effect for driving forces with different spectral content. At low frequencies (∼100 Hz) we obtained smooth rectification curves V_dc(I_ac) for different amplitudes of the potential and driving shapes. For monochromatic high frequency drive the rectified voltage becomes quantized. At very high frequencies we also observe half-period dynamics, current reversal and chaotic behavior. Such effects can be reproduced in simulation and associated with the inertial mass of a fluxon.

[1] E. Goldobin et al., Phys. Rev. E 63, 031111 (2001).