A Mach-Zehnder interferometer based tuning fork microwave impedance microscope

TL;DR

This paper presents an enhanced microwave impedance microscope using a tuning-fork based interferometer, offering improved signal quality and tunability, suitable for extreme environment applications where optical detection is challenging.

Contribution

The authors develop a novel interferometer-based microwave impedance microscope integrated with a tuning-fork SPM, improving signal-to-noise ratio and frequency tunability over previous designs.

Findings

Enhanced signal-to-noise ratio achieved

Wider microwave frequency tunability demonstrated

Suitable for operation in extreme environments

Abstract

We describe here the implementation of an interferometer-based microwave impedance microscope on a home-built tuning-fork based scanning probe microscope (SPM). Tuning-fork based SPMs, requiring only two electrical contacts for self-actuation and self-detection of the tuning fork oscillation, are especially well suited to operation in extreme environments such as low temperatures, high magnetic fields or restricted geometries where the optical components required for conventional detection of cantilever deflection would be difficult to introduce. Most existing and commercially available systems rely on optical detection of the deflection of specially designed microwave cantilevers, limiting their application. A tuning-fork based microwave impedance microscope with a resonant cavity near the tip was recently implemented: we report here an enhancement that incorporates a microwave interferometer, which affords better signal to noise as well as wider tunability in terms of microwave frequency.