Confinement and quantization effects in nanosuperconductors

Abstract

A systematic study of the geometry dependent nucleation of superconductivity in nanoscaled superconductors is presented in this paper. The experimental T c (H) phase boundary is compared to theoretical calculations obtained in the framework of the linearized Ginzburg-Landau theory for different geometries (square, triangle, disk). The influence of the transformation of a square into a rectangle on the T c (H) phase boundary is analyzed. In elongated rectangles, a crossover from a linear to a parabolic field dependence of T c has been observed. The evolution of the superconducting state is studied in a perforated disk by varying the size of the hole. A transition from a one-dimensional to a two-dimensional regime is seen when increasing the magnetic field for disks with small holes.