An Inexpensive, Configurable Two-Tone Electron Spin Resonance Spectrometer

TL;DR

This paper introduces a low-cost, flexible ESR spectrometer built from off-the-shelf components, capable of broad and dual-frequency operation, demonstrated on a molecular nanomagnet.

Contribution

It presents a configurable, inexpensive ESR spectrometer design that operates over a wide frequency range and can be easily reconfigured via FPGA programming.

Findings

Successfully characterizes Cr$_7$Mn nanomagnet

Operates over broad frequency range including outside standard bands

Supports single and dual-frequency ESR measurements

Abstract

Electron spin resonance (ESR) is a powerful tool for characterizing and manipulating spin systems, but commercial ESR spectrometers can be expensive and designed to work in narrow frequency bands. This work presents an inexpensive spectrometer that, when coupled with easy-to-design resonators, enables ESR over a broad frequency range, including at frequencies outside the standard bands. It can operate at either a single frequency or at two frequencies simultaneously. The spectrometer is built from off-the-shelf parts and controlled by a field programmable gate array (FPGA), and new capabilities can be easily added by reconfiguring the FPGA and adding or swapping components. We demonstrate the capabilities of the spectrometer using the molecular nanomagnet Cr$_7$Mn.