Study on the structural relaxation of vortex state due to the flux creep in high T c superconductors

Abstract
The deviation of magnetization (M) relaxation from logarithmic time dependence is due to both the low pinning potential influenced by the driving energy formed by the gradient of flux lines and the large thermal activation. Considering the structural relaxation of the vortex state under the action of the driving force and thermal activation, the dependence of M on time t can be obtained as M=A+Bt−β, where A, B, and β keep constant at a given field and temperature.