Numerical simulations on a two-dimensional lattice and self-organized criticality in high-T_c superconductors

Abstract

Flux motion in high-T_c superconductors with a random potential and a wide range of driving forces exhibits a dynamic crossover between different states. Numerical calculations provide evidence that the random hopping processes of the flux lines have the signatures of a self-organized critical state multiscale response of the system to small driving forces. Simulations of flux lines in a two-dimensional lattice were compared with the different superconducting systems of YB₂Cu₃O₇-Δ and 2H-NbSe₂. Critical exponents calculated from the relationship between driving forces and the average drift velocity of flux lines were found to be consistent with experimental data on Z—V characteristics of the superconductors.