Size effect on flux creep in Bi2Sr2CaCu 2O8+y

The sample size effect on the flux pinning and vortex dynamics has been studied on micron-sized Bi2Sr2CaCu2O 8+y crystals. The second magnetization peak (SMP) and the magnetic relaxation rate change with the sample size. A crossing point is found in field dependence of the normalized magnetic relaxation rate S for samples with different sizes. There is a sudden increase of S at the SMP field, which possibly originates from the propagation of phase boundary of vortex matter at the SMP field. © 2006 American Institute of Physics.