Thermally activated flux motion in MgCNi3

The time decay of the non-equilibrium magnetization of superconductor MgCNi3 is studied. It is found that the superconducting diamagnetic moment is logarithmically dependent on time. The nearly linear dependence of the normalized magnetization relaxation rate S on T suggests that the flux motion in MgCNi3 is described by the thermally activated mechanism. The relation between activation energy and current density is obtained by using Maley's technique.