Supercapacitance and Superinductance of TiN and NbTiN films in the Vicinity of Superconductor-to-Insulator Transition

We investigate the low temperature complex impedance of disordered insulating thin TiN and NbTiN films in the frequency region 400 Hz–1MHz in close proximity to the superconductor-insulator transition. The frequency, temperature, and magnetic field dependence of the real and imaginary parts of the impedance indicate the response of superconducting droplets resulting from self-induced electronic granularity. The impedance crosses over from capacitive to inductive behavior as the sample is driven through the transition, characterized by a divergent dielectric response.