Microwave cavity tuned with liquid metal and its application to Electron Paramagnetic Resonance

TL;DR

This paper introduces a method to tune microwave cavity resonant frequency using liquid metal, enabling EPR measurements by coupling with YIG spheres, with potential applications in GHz-range resonant systems.

Contribution

A novel tuning technique for microwave cavities using liquid metal GaInSn to adjust resonant frequencies in the GHz range for EPR applications.

Findings

Resonant frequency shifted in the 7-8 GHz range.

Successful coupling with YIG sphere for EPR measurement.

Demonstrated tunability of the cavity using liquid metal.

Abstract

This note presents a method to tune the resonant frequency $f_{0}$ of a rectangular microwave cavity. This is achieved using a liquid metal, GaInSn, to decrease the volume of the cavity. It is possible to shift $f_{0}$ by filling the cavity with this alloy, in order to reduce the relative distance between the internal walls. The resulting modes have resonant frequencies in the range $7\div8\,$GHz. The capability of the system of producing an Electron Paramagnetic Resonance (EPR) measurement has been tested by placing a 1 mm diameter Yttrium Iron Garnet (YIG) sphere inside the cavity, and producing a strong coupling between the cavity resonance and Kittel mode. This work shows the possibility to tune a resonant system in the GHz range, which can be useful for several applications.