Critical current density for superconductors with giant flux creep

• Published in: Cryogenics (Guildford) Vol. 36; no. 7; pp. 507 - 511
• Main Authors: Ding, Q., Xu, J.J., Ren, C., Shao, H.M., Lin, J.W., Ding, S.Y.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1996; Elsevier
• Subjects: Activation energy; Applied sciences; Creep; Critical current density (superconductivity); Electric fields; Electrical engineering. Electrical power engineering; Exact sciences and technology; Frequencies; giant flux creep; Hysteresis; Magnetic fields; Magnetization; Materials; Mathematical models; Mercury compounds; Superconducting transition temperature; superconductors; giant flux creep; J c; superconductors; Critical current density; Creep; Multielement compound; Magnetic hysteresis; Critical temperature; Critical field; Frequency effect; High temperature superconductor; Alternating current
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/0011-2275(96)00009-4

Critical current density J c is studied for superconductors with giant flux creep. It is shown that there do exist J c for such superconductors and the J c is determined by the effective activation energy U of flux diffusion rather than by the force of flux pinning. A procedure is proposed to determine J c as a function of field H d, temperature T and criterion f c if U is known. It is found that such J c are more dependent upon criterion at high frequency f c than at low f c. The J c( H d T) curves of HgBa 2Ca 2Cu 3O y at two criterions are estimated from the AC susceptibility data. The one with lower f c agrees well with the J c of the hysteresis measurement with the same criterion, whereas the other J c with higher f c is significantly higher than the former and may decay quickly. The present study not only shows the importance of the criterion for such J c but also that Hg-1223 is one of the more promising high- T c materials from a practical standpoint because of its high J c and T c.