Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 15: Superconductivity: Poster Session
TT 15.38: Poster
Tuesday, February 26, 2008, 14:00–18:00, Poster B
Spectroscopy of the eigenfrequencies of a fractional Josephson vortex molecule — •Uta Kienzle1, Tobias Gaber1, Kai Buckenmaier1, Konstantin Ilin2, Michael Siegel2, Dieter Koelle1, Reinhold Kleiner1, and Edward Goldobin1 — 1Physikalisches Institut - Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen — 2Institut für Mikro- und Nanoelektronische Systeme, Universität Karlsruhe (TH)
Using a pair of tiny current injectors one can create an arbitrary κ discontinuity of the phase in a long Josephson junction (LJJ) [1]. To compensate this discontinuity a κ vortex spontaneously appears [2]. This vortex carries an arbitrary fraction ∝ κ of the magnetic flux quantum Φ0 and is a generalization of a semifluxon observed in 0-π LJJs [3]. Such a vortex is pinned at the discontinuity point, but in an underdamped system it is able to oscillate around its equilibrium position with an eigenfrequency [4,5]. In annular LJJs with two injector pairs two coupled κ vortices, forming a molecule, can be studied.
The dependence of the eigenfrequency on temperature and κ of one and two coupled vortices was measured in the range from 300 mK up to 4.2 K. We discuss the results and compare them with simulations based on the perturbed sine-Gordon equation.
[1] E. Goldobin et al., Phys. Rev. Lett. 92, 57005 (2004)
[2] E. Goldobin et al., Phys. Rev. B 70, 174519 (2004)
[3] H. Hilgenkamp et al., Nature 422, 50 (2003)
[4] E. Goldobin et al., Phys. Rev. B 71, 104518 (2005)
[5] K. Buckenmaier et al., Phys. Rev. Lett. 98, 117006 (2007)