Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 36: Superconductivity - Vortex Dynamics, Vortex Phases, Pinning
TT 36.4: Talk
Wednesday, March 9, 2005, 10:45–11:00, TU H2053
Vortex Matching due to Periodic Pinning Center Arrays produced by Micellar Techniques — •J. Eisenmenger, M. Oettinger, C. Pfahler, C. Dietrich, F. Weigl, B. Koslowski, A. Plettl, H.-G. Boyen, A. Ethirajan, and P. Ziemann — Abteilung Festkörperphysik, Universität Ulm, 89069 Ulm
It has been demonstrated that pinning centers can lead to an enhanced stability of a vortex lattice, if this lattice matches a regular array of pinning centers without disturbing its preferred triangular order. Less explored are these phenomena at T ≪ Tc where effective pinning centers should exhibit sizes in the nm-range, which are difficult to achieve with conventional lithography methods. To produce triangular arrays of pinning centers we use metal-salt loaded inverse micelles of diblock-copolymers. The metal islands are prepared by immersion of the sample into a solution of diblock-copolymer micelles in toluene which were loaded with a defined amount of metal precursor. Subsequent plasma-etching removes the polymer and reduces the precursor salt to metal islands with a size of about 10 nm. Such supported metal nano particles can be used in different ways to produce pinning centers in superconductors. One approach is overgrowing the metal islands directly with a superconducting (SC) layer, producing pinning centers by locally changed SC properties. In a second approach, nano particles serve as etching masks to pattern arrays of nano columns into the surface of the substrate. These columns are used to locally influence the SC properties of a thin film grown on top. A third possibility is pressing a sample with nano columns into a SC film leading to an array of antidots.