Numerical simulations of elastic properties of flux-line lattices in high-T-c superconductors

We propose a quantitative model of the effective interaction between the ma gnetic flux-lines in a layered superconductor. It is derived from the Lawre nce-Doniach model with all of its parameters derivable from experiments. Nu merical simulations are performed using Langevin dynamics technique for par ameters suitable for Bi-2212. We studied the elastic properties of flux lin e lattices with various values of interlayer coupling strength and pinning strengths. We show that the "softening" of the flux-line lattices with incr easing temperature is mainly due to the increase of configurational entropy of the lattice. The calculated results show good agreement with experiment al observations and provide a unique way to study the properties of flux-li ne lattices with random pinning.