Hamburg 2001 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 12: Fachsymposium 2: Künstliche Pinning Zentren
TT 12.4: Vortrag
Dienstag, 27. März 2001, 15:45–16:00, J
Periodic vortex matching in YBa2Cu3O7−δ thin films by self-assembled triangular pinning arrays — •J. Eisenmenger1, G. Lengl1, H.-J. Kutschera1, F.-M. Kamm1, A. Plettl1, P. Ziemann1, J. Spatz2, S. Mössmer2, and M. Möller2 — 1Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm — 2Abteilung Organische Chemie III, Universität Ulm, D-89069 Ulm
We observed vortex matching effects in YBa2Cu3O7−δ thin films which were prepared with a triangular defect array. The periodic arrangement of artificial pinning centers were not patterned by conventional lithography. Rather, hexagonally self-assembled gold nano-islands on SrTiO3 substrates were used as inhibit structures for artificial periodic pinning centers in epitaxially grown YBa2Cu3O7−δ thin films (18 nm thick) which were deposited on such prepared substrates. The self-assembled gold islands were prepared by immersion of the SrTiO3 substrate into a dilute solution of diblock-copolymer micelles which were loaded with a defined amount of gold precursor. Subsequent plasma-etching removed the polymer and reduced the metal ions to gold islands with a height of 9 nm. Electrical transport measurement show that the critical current as a function of the applied magnetic field is enhanced when the lateral island-island distance (113 nm) corresponds to integer multiples of the vortex-vortex distance. The matching effects could be observed even at 7 K well below the critical temperature. This indicates that the pinning centers are small enough acting as very effective pinning centers even at the decreased coherence and penetration length at lower temperatures.