Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 23: Posters Superconductivity, Solids at Low Temperature
TT 23.39: Poster
Montag, 7. März 2005, 14:00–18:00, Poster TU D
Non-ideal artificial phase discontinuity and fractional vortex dynamics in long Josephson 0-κ-junctions. — •Edward Goldobin1, Tobias Gaber1, Dieter Koelle1, Reinhold Kleiner1, Michael Siegel2, and Manfred Neuhaus2 — 1Physikalisches 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 the creation of an arbitrary κ-discontinuity of the Josephson phase in a long Nb-AlOx-Nb Josephson junction (LJJ) using a pair of tiny current injectors, and study the formation of fractional vortices formed at this discontinuity. The current Iinj, flowing from one injector to the other, creates a phase discontinuity κ∝ Iinj. The calibration of injectors is discussed in detail. The small but finite size of injectors leads to some deviations of the properties of such a 0-κ-LJJ from the properties of a LJJ with an ideal κ-discontinuity. These experimentally observed deviations in the dependence of the critical current on Iinj and magnetic field can be well reproduced by numerical simulation assuming a finite injector size. The physical origin of these deviations is discussed. Furthermore, we present new experimental results on the dynamics of arbitrary fractional vortices and report the observation of semi-integer zero field steps corresponding to n=3/2 and n=5/2.