Confinement and Quantization Effects in Mesoscopic Superconducting Structures

TL;DR

This paper investigates how nanostructuring and topology influence the confinement and quantization effects in mesoscopic superconductors, revealing a unique relationship between sample shape and the critical temperature versus magnetic field phase boundary.

Contribution

It introduces a systematic study of different nanostructured superconductors, demonstrating how topology modifies the confinement effects and the T_c(H) phase boundary.

Findings

Shape of T_c(H) is determined by confinement topology

Topology variation affects the lowest Landau level E_LLL(H)

Confinement effects are consistent across different nanostructures

Abstract

We have studied quantization and confinement effects in nanostructured superconductors. Three different types of nanostructured samples were investigated: individual structures (line, loop, dot), 1-dimensional (1D) clusters of loops and 2D clusters of antidots, and finally large lattices of antidots. Hereby, a crossover from individual elementary "plaquettes", via clusters, to huge arrays of these elements, is realized. The main idea of our study was to vary the boundary conditions for confinement of the superconducting condensate by taking samples of different topology and, through that, modifying the lowest Landau level E_LLL(H). Since the critical temperature versus applied magnetic field T_c(H) is, in fact, E_LLL(H) measured in temperature units, it is varied as well when the sample topology is changed through nanostructuring. We demonstrate that in all studied nanostructured superconductors the shape of the T_c(H) phase boundary is determined by the confinement topology in a unique way.