Two-step depinning and re-entrant behavior of three-dimensional flux line lattices

Department of Physics, Southeast University - Nanjing 210096, China

Corresponding author: mliu@seu.edu.cn

Received: 1 November 2007
Accepted: 27 March 2008

Abstract

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.