Irreversibility line and magnetic field dependence of the critical current in superconducting MgB

Daniele Di Gioacchino, Umberto Gambardella, Paolo Tripodi, Gaia Grimaldi

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Abstract

The third harmonic components of the ac susceptibility of MgB2 bulk samples have been measured as a function of applied magnetic fields, together with standard magnetization cycles. The irreversibility line (IL) of the magnetic field has been extracted from the onset of the third harmonic components. Using a (1 - t)a glass/liquid best fit where α = 1.27 IL shows a coherent length ξ divergence with exponent v = 0.63, which indicates a 3D behaviour. Moreover, using the numerical solution of the non-linear magnetic diffusion equation, considering the creep model in a 3D vortex glass, a good description of the vortex dynamics has been obtained. The behaviour of the magnetization amplitude (∼Hz) and the ac susceptibility signals (kHz), at different applied magnetic fields, 3.5 T < Hdc < 4.5 T, and at the reduced temperature 0.86 < t < 0.93 (T = 22 K), shows that the superconducting dynamic response of vortices in the MgB2 samples is not evidently dependent on the frequency.
Original languageEnglish
Pages (from-to)534 - 537
Number of pages4
JournalSuperconductor Science and Technology
Volume16
Issue number4
DOIs
Publication statusPublished - Apr 2003
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Materials Chemistry
  • Electrical and Electronic Engineering

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