Frustration-induced disorder of flux-line structures in layered superconductors

As an example of a system with competing (frustrated) interactions, we study a model of the spatial arrangement of flux lines in a layered superconductor, with the magnetic field parallel with the layers, and in the limit of strong pinning to the layers. In this approach, we approximate the energy-minimization problem by a discrete nonlinear dynamical system, in which a vortex structure is built up one layer at a time. We find a complex variety of metastable states nearly degenerate with the ground state, including lattices with unit cells of many layer spacings, and disordered structures which correspond to chaotic trajectories of the dynamical map. The latter case provides an example of (metastable) quenched disorder in a model with no intrinsic randomness.