# Dresden 2006 – wissenschaftliches Programm

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# TT: Tiefe Temperaturen

## TT 33: Superconductivity: Vortex Dynamics, Vortex Phases, Pinning

### TT 33.2: Vortrag

### Freitag, 31. März 2006, 10:30–10:45, HSZ 304

**Temperature Dependent Matching in a Periodic Pinning Lattice with Disorder** — •J. Eisenmenger^{1}, M. Oettinger^{1}, C. Steiner^{1}, C. Pfahler^{1}, A. Plettl^{1}, H.-G. Boyen^{1}, A. Ethirajan^{1}, P. Walther^{2}, and P. Ziemann^{1} — ^{1}Abteilung Festkörperphysik, Universität Ulm, D-89069 Ulm, Germany — ^{2}Zentrale 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 *I*_{c} 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 *B*_{1} =
(2 Φ_{0})/ (√(3) *a*^{2}) only depends on the lattice constant *a* of the
APCs and the flux quantum Φ_{0}, 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.