Critical current densities and irreversibility field of high-Tc Ba2Ca3Cu4O(O,F)2 superconductor

Abstract

The superconductivity in apical fluorine system of Ba2Ca3Cu4O10-yFy: the fourth member of Ba2Can-1CunO2n(O,F)2 homologous series is significant to study as it deals with the novel phenomenon of superconductivity like co-existence of superconductivity and antiferromagnetism, in-equivalent and non-similar charge distribution in the CuO2 planes in a unit cell etc. The polycrystalline samples of Ba2Ca3Cu4O8(O,F)2 (F-0234) were synthesized under high pressure and showed sharp superconducting transitions temperature at 105 K. From the DA magnetization hysteresis loops, we determined the intragrain critical current density (Jc) and irreversibility field (Birr) using Bean's critical state model. The irreversibility line(IL) of F-0234 is higher than that for optimally-doped Bi-2212. However, IL much lower than that of Cu-1212 (Y-123) although the spacing of F-0234 (7.3 Å) is much thinner than that of Cu-1212.