Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.5: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Detailed studies of the resistive superconducting transition in UNi2Al3 thin films — •Michael Foerster, Martin Jourdan, Andrey Zakharov, and Hermann Adrian — Johannes Gutenberg-Universität, Institut für Physik, Mainz, Germany
Some time ago a dependence of the resistive superconducting transition temperature on the current direction in UNi2Al3 thin films was observed. Although a qualitative explanation can be given, fundamental questions about this phenomenon are still open, which motivated more detailed studies.
Morphological investigations by AFM and STM seem to rule out a growth mechanism induced origin. By using a specially designed photomask we were able to measure the transition down to current densities of 0.1 A/cm2 and observed no vanishing of the difference in Tc. However, the magnitude of the splitting of the sc transition varies from sample to sample without any correlation to the defect density as determined by the residual resistance ratio. V(I) characteristics in the superconducting state were measured at various magnetic fields, indicating anisotropic pinning. For the current direction I||c a thermally activated flux flow region could be identified.
Additional measurements with higher current densities prove that the observations in the relevant range are not generated by heating effects. The shift in Tc as a function of current density agrees well with the expectation for pairbreaking critical current from Ginzburg-Landau theory.