FLUX CREEP, PINNING POTENTIAL AND CRITICAL CURRENT-DENSITY IN BI2SR2CA1CU2OX SINGLE-CRYSTALS

Flux creep characteristic at 4.4 K in Bi2Sr2Ca1Cu2O(x) single crystals grown by flux method has been measured as a function of magnetic field applied parallel to the c-axis. The logarithmic relaxation rate of the magnetization dM/d ln t is analyzed on the basis of the flux creep model in combination with an extended Bean's critical state model in which n-th power dependence (0 less-than-or-equal-to n less-than-or-equal-to 1) of critical current density on magnetic field is assumed. The pinning potential and the zero-temperature critical current density are estimated to be 0.014 approximately 0.056 eV and 10(4) approximately 10(5) A/cm2, respectively, depending on oxygen partial pressure of the crystal growth environment.