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TT: Fachverband Tiefe Temperaturen
TT 58: SC: Vortex Dynamics, Vortex Phases, Pinning
TT 58.3: Talk
Thursday, March 17, 2011, 18:00–18:15, HSZ 301
Vortex attraction and vortex clusters — •Ernst Helmut Brandt — Max-Planck-Institut für Metallforschung, Stuttgart
While the Abrikosov vortices in superconductors usually repel
each other, there are cases when the vortex interaction has
an attractive tail and thus a minimum. This may lead to vortex
clusters and chains. Decoration pictures then may look like
in the intermediate state of type-I superconductors, showing
lamellae or islands of Meissner state or surrounded by Meissner
state, but now the normal regions are filled with Abrikosov
vortices that are typical for type-II superconductors in the
mixed state. Such intermediate-mixed state was observed and
investigated in detail in pure Nb, TaN and other materials
40 years ago [1-3]. Recently it was possibly also observed in
MgB2 [4] where it was simply ascribed to the existence
of two superconducting electron bands, one of type-I and one of
type-II. We expect [5] that the complicated two-band electronic
structure of MgB2 possessing a single transition temperature
may indeed lead to vortex interaction with an attractive tail
if evaluated numerically.
[1] U. Essmann and H. Träuble, Sci. Am. 224, 75 (1971).
[2] J. Auer and H. Ullmaier, Phys. Rev. B 7, 136 (1973).
[3] E. H. Brandt and U. Essmann, phys. stat. sol.(b) 144,
13-38 (1987).
[4] V. Moshchalkov et al., Phys. Rev. Lett. 102, 117001
(2009).
[5] E. H. Brandt and M. P. Das, Journal of Superconductivity and
Novel Magnetism, in print.