INFLUENCE OF THE FLUX CREEP ON THE CRITICAL CURRENT-DENSITY IN BI2SR2CA2CU3OX AND Y(HO)BA2CU3OY SUPERCONDUCTORS

Intragrain Jc values of the textured Bi- and Y-based oxides were obtained at 4.2 K–77 K by the D.C. magnetization measurements with various sweep rates of the magnetic field. The Jc's at 4.2 K were comparable for both oxides. However, with increasing temperature, the Jc of the Bi-based oxide became much more sensitive to the electric field criterion Ec related to the sweep rate of the magnetic field than that of the Y-based oxide. As a result, Jc at 77 K of the Bi-based oxide was significantly decreased in magnetic fields for small Ec. The dependence of Jc on Ec for both oxides can be well understood using the flux creep model. © 1990 The Japan Society of Applied Physics.