Dependence of the flux-creep activation energy on current density and magnetic field for the MgB2 superconductor

Authors

M. J. Qin, University of WollongongFollow
Xiaolin Wang, University of WollongongFollow
Saeid Soltanian, University of WollongongFollow
Aihua Li, 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, Soltanian, S, Li, AH, Liu, HK & Dou, SX, Dependence of the flux-creep activation energy on current density and magnetic field for the MgB2 superconductor, Physical Review B, 2001, 64, 060505(R). Copyright 2001 American Physical Society. The original journal can be found here.

Abstract

Systematic ac susceptibility measurements have been performed on a MgB₂ bulk sample. We demonstrate that the flux creep activation energy is a nonlinear function of the current density U(j)∝j^-0.2, indicating a nonlogarithmic relaxation of the current density in this material. The dependence of the activation energy on the magnetic field is determined to be a power law U(B)∝B^-1.33, showing a steep decline in the activation energy with the magnetic field, which accounts for the steep drop in the critical current density with magnetic field that is observed in MgB₂. The irreversibility field is also found to be rather low, therefore, the pinning properties of this material will need to be enhanced for practical applications.