Optimized Broadband Cryogenic Ferromagnetic Resonance Spectrometer using a Closed Cycle Refrigerator

TL;DR

This paper introduces a cost-effective, broadband cryogenic ferromagnetic resonance spectrometer operating up to 20 GHz from 11 to 350 K, utilizing a closed cycle refrigerator and custom waveguide for reliable measurements.

Contribution

The paper presents a novel integrated cryogenic FMR spectrometer with a custom waveguide and calibration method, enabling broadband operation and high sensitivity at cryogenic temperatures.

Findings

Successfully measured FMR spectra of YIG thin film

Achieved narrow linewidths indicating high sensitivity

Operated reliably over wide temperature and frequency range

Abstract

We present a vector network analyzer (VNA) based broadband cryogenic ferromagnetic resonance (FMR) spectrometer, operating up to 20 GHz over a temperature range of 11 to 350 K. A cost effective architecture is implemented through the integration of a closed cycle refrigerator (CCR) and a custom fabricated grounded coplanar waveguide (GCPW), designed for broadband transmission and reliable cryogenic operation. The VNA calibration is performed prior to measurements to account for microwave background and transmission losses, enabling reliable extraction of FMR spectra across the full temperature / frequency range. The sensitivity of the spectrometer is benchmarked using a yttrium iron garnet (YIG) thin film, yielding well resolved resonances with narrow linewidths and high sensitivity.