Homogeneous superconducting phase in TiN film : a complex impedance study

TL;DR

This study investigates the complex impedance of a TiN superconducting film, revealing a homogeneous superconducting phase consistent with BCS theory and demonstrating a linear relationship between resonator quality factor and temperature-induced frequency changes.

Contribution

It provides experimental evidence of a homogeneous superconducting phase in TiN films using complex impedance measurements and GHz microresonators, confirming BCS behavior and a two-fluid model description.

Findings

Superconducting gap is well-defined and consistent with BCS theory.

Homogeneous superconducting phase observed in TiN far from disorder transitions.

Linear correlation between resonator quality factor and temperature changes.

Abstract

The low frequency complex impedance of a high resistivity 92 {\mu}{\Omega} cm and 100 nm thick TiN superconducting film has been measured via the transmission of several high sensitivity GHz microresonators, down to Tc/50. The temperature dependence of the kinetic inductance follows closely BCS local electrodynamics, with one well defined superconducting gap. This evidences the recovery of an homogeneous superconducting phase in TiN far from the disorder and composition driven transitions. Additionally, we observe a linearity between resonator quality factor and frequency temperature changes, which can be described by a two fluid model.