Evidence for vortex pinning induced by fluctuations in the transition temperature of MgB2 superconductors

Authors

M. J. Qin, University of WollongongFollow
Xiaolin Wang, University of WollongongFollow
Hua-Kun Liu, University of WollongongFollow
S. X. Dou, Univeristy of WollongongFollow

Publication Details

This article was originally published as: Qin, MJ, Wang, XL, Liu, HK & Dou, SX, Evidence for vortex pinning induced by fluctuations in the transition temperature of MgB2 superconductors, Physical Review B, 2002, 65, 132508. Copyright 2002 American Physical Society. The original journal can be found here.

Abstract

The field-dependent critical current density j_c(B) of a MgB₂ bulk sample has been obtained using magnetic measurements. The j_c(B) curves at different temperatures demonstrate a crossover from single vortex pinning to small-bundle vortex pinning, when the field is larger than the crossover field B_sb. The temperature dependence of B_sb(T) is in agreement with a model of randomly distributed weak pinning centers via the spatial fluctuations of the transition temperature (δT_c pinning), while pinning due to the mean-free-path fluctuations (δl pinning) is not observed.