Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Superconductivity - Vortex Dynamics, Vortex Phases, Pinning
TT 34.1: Vortrag
Freitag, 30. März 2007, 10:15–10:30, H19
Commensurability effects in Nb thin films with (quasi-)periodic pinning arrays — •Matthias Kemmler1, Daniel Bothner1, Albert Sterck1, Michael Siegel2, Reinhold Kleiner1, and Dieter Koelle1 — 1Physikalisches Institut - Experimentalphysik II,Universität Tübingen, Auf der Morgenstelle 14, D-72076Tübingen — 2IMS, Universität Karlsruhe,Hertzstr. 16, D-76187 Karlsruhe
We study experimentally the critical depinning current Ic versus applied magnetic field B in Nb thin films which contain 2D arrays of circular antidots placed on the nodes of a fivefold Penrose lattice.
For measurements of electric transport we use a highly sensitive liquid Helium-cooled dc SQUID amplifier. The sample temperature is controlled and stabilized close to the Nb transition temperature Tc via an optical, very low noise heating system.
Our experiments confirm essential features in the Ic(B) patterns as predicted by Misko et al.[1] , close to the transition temperature Tc of the Nb films.
In order to find the arrangement of optimal pinning we compare the performance of Nb films containing quasiperiodic pinning arrays, triangular pinning arrays, randomly distributed antidots, or no antidots. Some of the results are published in [2].
[1] V.R. Misko, S.Savel’ev, F.Nori, Phys. Rev. Lett. 95 (2005) 177007
[2] M. Kemmler et al., Phys. Rev. Lett. 97 (2006) 147003