Force-detected high-frequency electron spin resonance spectroscopy using magnet-mounted nanomembrane: robust detection of thermal magnetization modulation

TL;DR

This paper introduces a novel broadband high-frequency ESR spectroscopy method that detects thermal magnetization changes, demonstrating high sensitivity and stable operation at high magnetic fields, suitable for advanced research applications.

Contribution

The study presents a new force-detected HFESR technique based on thermal magnetization modulation, enabling stable measurements at high magnetic fields with high sensitivity.

Findings

Successfully measured ESR spectra at 15 T and 636 GHz without distortion.

Achieved a spin sensitivity of 10^12 spins/G·s, independent of relaxation times.

Demonstrated stable operation of the spectrometer at high magnetic fields.

Abstract

In this study, we report a conceptually novel broadband high-frequency electron spin resonance (HFESR) spectroscopic technique. In contrast to the ordinary force-detected ESR technique, which detects the magnetization change due to the saturation effect, this method measures the magnetization change due to the change of the sample temperature at resonance. To demonstrate its principle, we developed a silicon nitride nanomembrane-based force-detected ESR spectrometer, which can be stably operated even at high magnetic fields. Test measurements were performed for samples with different spin relaxation times. We succeeded in obtaining a seamless ESR spectrum in magnetic fields of 15~T and frequencies of 636~GHz without significant spectral distortion. A high spin sensitivity of $10^{12}$~spins/G$\cdot$s was obtained, which was independent of the spin relaxation time. These results show that this technique can be used as a practical method in research fields where the HFESR technique is applicable.