Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 9: SC: Poster Session
TT 9.27: Poster
Montag, 22. März 2010, 14:00–18:00, Poster A
Local visualization of the disordered vortex lattice in overdoped BaFe2−xCoxAs2 superconductor — •Henry Stopfel1, Tetyana Shapoval1, Dmytro S. Inosov2, Volker Neu1, Ulrike Wolff1, Silvia Haindl1, Konstantin Nenkov1, Bernhard Holzapfel1, Ji Tae Park2, Dunlu L. Sun2, Chengtian T. Lin2, Vladimir Hinkov2, and Ludwig Schultz1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden, Germany — 2Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
Using low temperature magnetic force microscopy (MFM) we imaged the vortex distribution in a slightly overdoped BaFe2−xCoxAs2 (x = 0.19, Tc = 23 K) superconducting single crystal [1]. Our local method reveals that at low fields (3 mT und 6 mT) the superconducting flux lines arrange in a vortex glass phase with only a short-range order. This denotes a presence of pinning centres which prohibit a formation of the ordered Abrikosov lattice. From the statistical processing of MFM data we have extracted the radial correlation length ζ of the vortex lattice and have established the hexagonal local lattice symmetry. It reveals that the visualized vortex distribution can be treated as a disordered triangular lattice. Moreover, the isothermal magnetization loops measured at various temperatures in a wide field range up to 14 T exhibit the “fishtail” effect that is known to be related to the vortex pinning and to the crossover between two different regimes of the vortex lattice.
[1] D. S. Inosov, T. Shapoval, V. Neu, et al., arXiv:0911.1971v1 (2009).