Large Microwave Inductance of Granular Boron-Doped Diamond Superconducting Films

TL;DR

This study measures the microwave surface impedance of boron-doped diamond superconducting films, revealing their high inductance and potential for quantum and microwave applications.

Contribution

It provides the first detailed microwave impedance measurements of boron-doped diamond films, linking inductance to normal state resistance and confirming s-wave superconductivity.

Findings

Inductance values match estimates from sheet resistance.

Magnetic penetration depth follows s-wave superconductor behavior.

Films exhibit high kinetic inductance suitable for quantum devices.

Abstract

Boron-doped diamond granular thin films are known to exhibit superconductivity with an optimal critical temperature of Tc = 7.2K. Here we report the measured complex surface impedance of Boron-doped diamond films in the microwave frequency range using a resonant technique. Experimentally measured inductance values are in good agreement with estimates obtained from the normal state sheet resistance of the material. The magnetic penetration depth temperature dependence is consistent with that of a fully-gapped s-wave superconductor. Boron-doped diamond films should find application where high kinetic inductance is needed, such as microwave kinetic inductance detectors and quantum impedance devices.