Regensburg 2007 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 8: Superconductivity - Poster Session

TT 8.33: Poster

Monday, March 26, 2007, 14:00–17:45, Poster A

Spectroscopy of the fractional vortex eigenfrequency in a long Josephson 0-κ junction — •Kai Buckenmaier¹, Tobias Gaber¹, Inga Schittenhelm¹, Michael Siegel², Reinhold Kleiner¹, Dieter Koelle¹, and Edward Goldobin¹ — ¹Physikalisches Institut, Experimentalphysik II, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, Germany — ²Universitaet Karlsruhe, Institut fuer Mikro– und Nanoelektronische Systeme, Hertzstr. 16, D-76187 Karlsruhe, Germany

In long Josephson junctions with a κ-phase discontinuity, created by two current injectors, a fractional Josephson vortex (FJV) is spontaneously formed at the interface between the 0- and κ-part. A FJV carrys an arbitrary fraction Φ/Φ₀=κ/2π of the magnetic flux quantum Φ₀ ≈ 2.07 × 10⁻¹⁵ Wb. In contrast to fluxons, FJVs are pinned at the discontinuity point, but in underdamped systems they are able to oscillate around their equilibrium point with characteristic eigenfrequencies. To experimentally determine the eigenfrequency we stimulated a FJV by irradiating our sample with microwaves. At resonance the junction switches to the resistive state. A measurement of the switching probability thus allows to determine the FJV eigenfrequency as a function of bias current and κ. We compare our results with the prediction of the pertubed sine-Gordon equation.