Field-enhanced critical parameters in magnetically nanostructured superconductorsM. V. Milosevic and F. M. Peeters
Departement Fysica, Universiteit Antwerpen (Campus Middelheim) Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
received 7 March 2005; accepted in final form 13 April 2005
published online 29 April 2005
Within the phenomenological Ginzburg-Landau theory, we demonstrate the enhancement of superconductivity in a superconducting film, when nanostructured by a lattice of magnetic particles. Arrays of out-of-plane magnetized dots (MDs) extend the critical magnetic field and critical current the sample can sustain, due to the interaction of the vortex-antivortex pairs and surrounding supercurrents induced by the dots and the external flux lines. Depending on the stability of the vortex-antivortex lattice, a peak in the Hext-T boundary is found for applied integer and rational matching fields, which agrees with recent experiments (LANGE M. et al. , Phys. Rev. Lett., 90 (2003) 197006). Due to compensation of MDs- and Hext-induced currents, we predict the field-shifted jc-Hext characteristics, as was actually realized in previous experiment but not commented on (MORGAN D. J. AND KETTERSON J. B., Phys. Rev. Lett., 80 (1998) 3614).
74.78.-w - Superconducting films and low-dimensional structures.
74.25.Dw - Superconductivity phase diagrams.
74.25.Qt - Vortex lattices, flux pinning, flux creep.
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