RESUMEN
Motivated by a diversity of the shape instability phenomena in condensed-matter physics, we study the formation of elastic ribbon structures and transformation into helicoidal structures. Using the multipulse laser-matter interaction with the Co-coated surface, a one-dimensional high-density vortex-filament array has been created. Increasing the number of pulses, the oscillatory strain field causes the cascade of the shape transformations into structures of increasing topological complexity: vortex filaments into ribbons, into ribbon helicoids and tubular-ribbon helicoids, and then into short ribbon structures with the complex Scherk surface being identified. The cascade of transformations follows the scenario in which the topological complexity of the new structure increases with the number of pulses, thus, realizing configurations with more efficient energy relaxation. Above a critical number of pulses, the system is catastrophically disintegrated into small-scale wrinkled and crumpled surfaces. We show that the critical parameter for the ribbon transformations is the number of laser pulses which is equivalent to some critical oscillatory frequency.
RESUMEN
The interaction of laser light with a metal surface yields a complex configuration of point defects, e.g., droplets and holes and vortex microfilaments. When a single filament interacts with a defect it "winds" around the defect and can form loops, and rings. Interaction of a single filament with a single defect gives rise to arc deformation bending, formation of loops and rings, while its interaction with a two-dimensional (2D) random lattice of defects gives rise to the vortex filament splitting and breaking which occur at nodal points of the Voronoi lattice. Interaction of one-dimensional (1D) vortex filament lattice with 2D lattice of defects results in the formation of knotted structures such as the Hopf links as well as 1D and 2D Hopf link crystals, knotted along the sides of the Voronoi lattice. We observed that configurations of vortex filaments are organized at three hierarchical levels of growing complexity. Every level is comprised of the elements of the lower complexity one, indicating the presence of a supercomplexity.
RESUMEN
The index of refraction of a-Si(1-x)C(x):H thin films obtained by dc magnetron sputtering was determined by means of IR absorption measurements. Structural and compositional changes that take place by increasing x make the film a mixture of different species, giving an effective value of the refractive index.