Investigation of collective creep in YBaCuO

Abstract

Time dependent decay of the magnetic moment M(t) and magnetization measurements were used to study flux creep in melt textured YBaCuO samples. From both measurements voltage current characteristics were reconstructed between 10 −1 and 10 −7 μV/cm up to the region of the irreversibility field. The exponent μ of the power law dependence of the pinning barrier was obtained from M(t) using the time constant of the initial stage of relaxation and from E(j) analysis. The current dependence of μ shows a maximum, negative values on both sides as well as the field dependence are not in agreement with theoretical predictions.