Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 33: Superconductivity: Vortex Dynamics, Vortex Phases, Pinning
TT 33.2: Talk
Friday, March 31, 2006, 10:30–10:45, HSZ 304
Temperature Dependent Matching in a Periodic Pinning Lattice with Disorder — •J. Eisenmenger1, M. Oettinger1, C. Steiner1, C. Pfahler1, A. Plettl1, H.-G. Boyen1, A. Ethirajan1, P. Walther2, and P. Ziemann1 — 1Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm, Germany — 2Zentrale Einheit Elektronenmikroskopie, Universität Ulm, D-89069 Ulm, Germany
We prepared a lattice of nanoscaled artificial pinning centers (APCs) into a Nb film. The patterning technique is based on self-organization of inverse micelles of diblock-copolymers on a substrate. The resulting lattice of APCs mirrors the order of the micellar array which is triangular on the short range, but loses its directional order for larger distances. A unique feature of such prepared samples is that, in contrast to perfectly ordered pinning arrays, the matching field, as defined by the field where the critical current Ic has a maximum, depends on temperature. At the first glance any temperature dependence is unexpected, since the value of matching field for a triangular lattice B1 = (2 Φ0)/ (√(3) a2) only depends on the lattice constant a of the APCs and the flux quantum Φ0, which both are temperature independent. Several possible interpretation of this unusual behavior are discussed. In particular it is considered that a is not a fixed value for the entire self-assembled APC lattice but varies over a certain range.