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

M. J. Qin, University of Wollongong
X. L. Wang, University of Wollongong
H. K. Liu, University of Wollongong
S. X. Dou, University of Wollongong

Article comments

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 jc(B) of a MgB2 bulk sample has been obtained using magnetic measurements. The jc(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 Bsb . The temperature dependence of Bsb(T) is in agreement with a model of randomly distributed weak pinning centers via the spatial fluctuations of the transition temperature ( Tc pinning, while pinning due to the mean-free-path fluctuations ( l pinning is not observed.