Study of the Irreversibility Line of GdBa2Cu3O7-delta Added with Nanosized Ferrite CoFe2O4

作者：Basma H^*; Awad R; Roumie M; I**er S; Marhaba S; AbouAly A I

来源：Journal of Superconductivity and Novel Magnetism, 2016, 29(1): 179-185.

DOI：10.1007/s10948-015-3244-x

• GdBa2Cu3O7-delta
• Nanoferrite CoFe2O4
• ac magnetic susceptibility
• Irreversibility line

(CoFe (2) O (4)) (x) GdBa Cu-2 (3) O (7-delta) superconducting samples were synthesized using a conventional solid-state reaction technique with 0a parts per thousand currency signxa parts per thousand currency sign0.1 wt%. Characterization of the prepared samples was carried out using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The effect of adding CoFe (2) O (4) to the Gd-123 phase, which acts as a flux pinning center, was investigated by measuring the ac magnetic susceptibility at different applied dc magnetic fields. Both the superconducting transition temperature T (c) and the critical current density J (c) increased up to x=0.01 wt%, and then, they decreased with further increase in x. The temperature dependence of the irreversibility line was investigated by the logarithmic plot of the irreversibility field H (irr) versus (1-T (irr)/T (c)(0)). This plot shows a crossover at a field of 1000 Oe, indicating 3D to 2D flux creep fluctuations. Furthermore, the H (irr)-T curves are well fitted according to a theoretical model proposed by Matsushita, based on the depinning mechanism caused by thermally activated flux creep.

• 出版日期2016-1