I Pallecchi et al 2009 Supercond. Sci. Technol. 22 015023 doi:10.1088/0953-2048/22/1/015023
I Pallecchi1, V Ferrando1, C Tarantini1, M Putti1, C Ferdeghini1, Ye Zhu2, P M Voyles2 and X X Xi3,4
Show affiliationsWe study the critical current density Jc of a series of MgB2 epitaxial thin films with disorder introduced in a controlled way by neutron irradiation. We find that the in-field Jc is significantly increased for an intermediate neutron fluence of ~7.6 × 1017 cm−2, reaching ~1.8 × 105 A cm−2 at μ0H = 4 T, which is larger by more than one order of magnitude than the critical current density of the pristine sample. Moreover, in the same irradiated sample, Jc(μ0H = 9 T) is still as large as 1.1 × 104 A cm−2. By transmission electron microscopy, we find evidence of the presence of amorphous regions created by irradiation whose average size matches the coherence length ξab. Analysis of the shape of the critical current density and pinning force curves indicates that such regions with a suppressed superconducting order parameter behave as effective point-like pinning centers for magnetic flux lines.
61.80.Hg Neutron radiation effects
74.25.Qt Vortex lattices, flux pinning, flux creep
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
Issue 1 (January 2009)
Received 14 October 2008, in final form 7 November 2008
Published 10 December 2008
I Pallecchi et al 2009 Supercond. Sci. Technol. 22 015023
J Y T Huang et al 2009 J. Phys. D: Appl. Phys. 42 025108