Dresden 2009 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 32: Postersession Superconductivity: Josephson Junctions, SQUIDs, Heterostructures, Andreev Scattering, Vortex Physics, Cryodetectors, Measuring Devices, Cryotechnique
TT 32.5: Poster
Wednesday, March 25, 2009, 14:00–18:00, P1A
A Josephson Vortex Ratchet climbs uphill — •Martin Knufinke1, Kai Buckenmaier1, Michael Siegel2, Dieter Koelle1, Reinhold Kleiner1, and Edward Goldobin1 — 1Physikalisches Institut – Center for Collective Quantum Phenomena, University of Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany — 2Institut für Mikro- und Nanoelektronische Systeme, Universität Karlsruhe (KIT), Hertzstr. 16, D-76187 Karlsruhe, Germany
A particle in a potential with broken reflection symmetry has a preferential direction of motion being driven by a deterministic or stochastic force with zero time-average [1]. Josephson vortex ratchets (JVRs) offer a flexible way of implementing such a system in the underdamped regime [2]. In a long annular Josephson junction the particle is a fluxon that moves in a potential created by a suitable current injection profile [3,4]. Due to the asymmetry of the resulting potential an ac current drive leads to a dc voltage across the Josephson junction.
Being in the rectification regime we apply an additional bias current which tilts the potential and pushes the fluxon in the direction opposite to its motion, i.e. the fluxon moves uphill due to the ratchet effect. At some value Istop of bias the fluxon stops. We determine Istop both experimentally and numerically and obtain information about the loading capability of the ratchet.
[1] P. Hänggi et al., Ann. Phys. (Leipzig) 14, 51 (2004)
[2] G. Carapella et al., Phys. Rev. Lett. 87, 077002 (2001)
[3] E. Goldobin et al., Phys. Rev. E 63, 031111 (2001)
[4] M. Beck et al., Phys. Rev. Lett. 95, 090603 (2005)