Evidence for Transition Temperature Fluctuation Induced Pinning im MgB₂ Superconductor

2001/08/10 by M. J. Qin, X. L. Wang, Qin, M. J. +5
Physics and Astronomy · #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con

paper · pdf · doi:10.48550/arxiv.cond-mat/0108172

11 pages, 6 figures

arxiv created 2001/08/10 · arxiv updated 2009/11/30

Abstract

The magnetic field dependent critical current density j_c(B) of a MgB₂ bulk sample has been obtained by means of magnetization hysteresis 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 the crossover field 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.

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