Thermally activated flux motion in high-T c superconductors

Using the modified Anderson-Kim theory of flux creep and the Bean model, we derive an analytical expression for magnetic relaxation of high-Tc superconductors, which is applicable in the whole flux creep region. The high driving force limit of the expression gives the usual logarithmic decay law and its low driving force limit takes the exponential form. Theoretical analysis is in agreement with the existing experimental results.