Evidence of a new low field cross-over in the vortex critical velocity of type-II superconducting thin films - Condensed Matter > SuperconductivityReportar como inadecuado




Evidence of a new low field cross-over in the vortex critical velocity of type-II superconducting thin films - Condensed Matter > Superconductivity - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We measure current-voltage characteristics as function of magnetic field andtemperature in Nb strips of different thickness and width. The instabilityvoltage of the flux flow state related to the vortex critical velocity v* isstudied and compared with the Larkin-Ovchinnikov theory. Beside the usualpower-law dependence v* ~ B^-1-2, in the low field range a new cross-overfield, Bcr1, is observed below which v* decreases by further lowering theexternal magnetic field B. We ascribe this unexpected cross-over to vortexchanneling due to a fan-like penetration of the applied magnetic field asconfirmed by magneto-optic imaging. The observation of Bcr1 becomes a directevidence of a general feature in type-II superconducting films at low fields,that is a channel-like vortex motion induced by the inhomogeneous magneticstate caused by the relatively strong pinning.



Autor: G. Grimaldi, A. Leo, D. Zola, A. Nigro, S. Pace, F. Laviano, E. Mezzetti

Fuente: https://arxiv.org/







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