Dielectric Response of a Superconductor Near Percolation

Superconductivity, Percolation, Microwave Spectroscopy, Criticality

Successively connecting isolated, conducting, microscopic islands eventually leads to percolation with macroscopic conduction. The macroscopically insulating state close to such an insulator-conductor transition can be strongly polarized and should exhibit a divergence of the dielectric constant when approaching this transition. In this project, we want to study this diverging dielectric constant near percolation for the case of a superconductor, namely Sn. We will use cryogenic microwave coplanar resonators as probes, which are covered with island-structured non-percolated Sn films, and we will study their dielectric response above and below the superconducting transition temperature.