Dresden 2011 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 46: SC: Tunneling, Josephson Junctions, SQUIDs 1
TT 46.7: Vortrag
Donnerstag, 17. März 2011, 12:15–12:30, HSZ 301
Thermal and Quantum depinning of a fractional Josephson vortex — •Edward Goldobin1, Tobias Gaber1, Kai Buckenmaier1, Uta Kienzle1, Hanna Sickinger1, Dieter Koelle1, Reinhold Kleiner1, Max Meckbach2, Christoph Kaiser2, Konstantin Il’in2, and Michael Siegel2 — 1Physikalische Institut, University of Tübingen, Auf der Morgenstelle 14, 72076 Tübingen — 2Institut für Mikro- und Nanoelektronische Systeme, University of Karlsruhe, Hertzstraße 16, 76187, Karlsruhe
We investigate the bias current induced depinning of a fractional Josephson vortex in a 0-κ Josephson junction [1], where the κ-discontinuity of the phase is induced by current injectors. At high temperatures T≳ 100 mK the depinning is governed by thermal fluctuations. By measuring a depinning current histogram and extracting the effective barrier height vs. κ, one can see the signatures of fractional vortex escape [2,3]. At low T ≲ 100 mK, the escape is dominated by quantum fluctuations and the histogram width saturates. In spite of large currents involved (bias current ∼ 1 mA, injector current ∼ 5 mA), advanced experimental techniques such as superconducting bias filters and persistent mode loops for injector currents allow us to argue that the observed histograms correspond to MQT of a fractional vortex. We also discuss the particular histogram shape in this quantum regime.
[1] E. Goldobin et al., Phys. Rev. B 70, 174519 (2004).
[2] U. Kinzle et al., Phys. Rev. B 80, 014504 (2009).
[3] K. Vogel et al., Phys. Rev. B 80, 134515 (2009).