Vortex dynamics and confinement phenomena in superconducting nanomaterials.

In this research project three different model systems with vortex ratchets will be investigated: periodic arrays of symmetric and asymmetric pinning sites, superconductor/ferromagnet hybrid nanosystems, and single element nanosuperconductors. We will use lithographic arrays and also arrays produced by hexagonally ordered two-dimensional nanopores arrays (made from anodic alumina) underlying a superconducting film. Matching-field effects, which occur when the average vortex density is commensurate with the density of pinning sites (pores), will be explored. In addition, by placing close to each other two nanoscale antidots of different dimensions the pinning symmetry is broken and vortex depinning and repinning will be realized preferentially along one direction. The dc response induced by an ac current drive will be studied for different sets of nanoengineered pinning sites as a function of temperature, ac drive frequency and amplitude. We shall also vary systematically the thickness of the superconducting film to induce the crossover from type-II to type-I superconductivity and to study vortex patterns and guided vortex motion for different film ticknesses. Molecular dynamics simulation as well as 2D and 3D Ginzburg-Landau theory will be used to model these systems and to analyze these experimental data.

Keywords:Vortex dynamics, Nano technology, Nano materials

Disciplines:Condensed matter physics and nanophysics