Two-step depinning and re-entrant behavior of three-dimensional flux line latticesZ. G. Zhao, Y. X. You, J. Wang and M. Liu
Department of Physics, Southeast University - Nanjing 210096, China
received 1 November 2007; accepted in final form 27 March 2008; published May 2008
published online 7 May 2008
We develop a three-dimensional flux line lattice (FLL) model with magnetic interactions between intraplane and interplane vortices to simulate the dynamic behavior of the flux flow in a disordered point-pinned system. A double-peak structure is found in the differential resistivity as a function of the driving current, corresponding to the two-step depinning behavior of the vortex motion. In between the two peaks there exists a new re-entrant pinning phase. The calculated results are summarized as a phase diagram of the interplane coupling strength of pancake vortices vs. the applied driving current. A huge peak effect and current-induced re-entrant pinning behavior appear in a narrow regime, where an unusual intrinsic pinning mechanism due to interlayer interactions dominates the peak effect. The phase diagram obtained is favorable for understanding the two-step depinning and re-entrant behavior observed recently experimentally.
74.25.Qt - Vortex lattices, flux pinning, flux creep.
74.25.Op - Mixed states, critical fields, and surface sheaths.
74.25.Dw - Superconductivity phase diagrams.
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