Cryogenic frequency-domain electron spin resonance spectrometer based on coplanar waveguides and field modulation

Area of Science:

• Physics
• Materials Science
• Spectroscopy

Background:

• Electron Spin Resonance (ESR) is a powerful technique for studying materials with unpaired electrons.
• Traditional ESR setups can face limitations in parameter space and signal sensitivity.

Purpose of the Study:

• To present a novel instrument for frequency-domain electron spin resonance (ESR) experiments.
• To demonstrate the instrument's capabilities across a wide range of frequencies, magnetic fields, and temperatures.
• To evaluate the effectiveness of field modulation in enhancing signal quality.

Main Methods:

• Utilizing coplanar waveguides for microwave delivery and detection.
• Implementing field modulation techniques to improve signal-to-noise ratio.
• Calibrating the instrument using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and assessing sensitivity with carbon fiber samples.

Main Results:

• The instrument covers a broad parameter space: frequency (up to 25 GHz), magnetic field (up to 8 T), and temperature (down to 1.6 K).
• Experiments on DPPH and carbon fiber validated the setup's functionality and sensitivity.
• Spectra of ruby samples showed a significant improvement in signal-to-noise ratio when field modulation was employed.

Conclusions:

• The developed frequency-domain ESR instrument offers a versatile platform for advanced material characterization.
• Field modulation is a key technique for enhancing ESR signal quality, particularly at cryogenic temperatures.
• This instrument enables new possibilities for exploring electron spin dynamics in diverse materials.