Spectroscopy of the parametric magnons excited by 4-wave process

TL;DR

This study uses a Magnetic Resonance Force Microscope to perform ferromagnetic resonance spectroscopy on parametric magnons generated by a 4-wave process, revealing ultra-narrow spectral peaks associated with magnon mode adjustments.

Contribution

It introduces a novel spectroscopic method to analyze parametric magnons created by 4-wave processes using differential response measurements.

Findings

Observation of abrupt magnon number readjustments at specific fields

Detection of ultra-narrow resonance peaks with linewidths below 5×10^{-6} of the applied field

Demonstration of the sensitivity of the technique to parametric magnon modes

Abstract

Using a Magnetic Resonace Force Microscope, we have performed ferromagnetic resonance (FMR) spectroscopy on parametric magnons created by 4-wave process. This is achieved by measuring the differential response to a small source modulation superimposed to a constant excitation power that drives the dynamics in the saturation regime of the transverse component. By sweeping the applied field, we observe abrupt readjustement of the total number of magnons each time the excitation coincides with a parametric mode. This gives rise to ultra-narrow peaks whose linewith is lower than $5~10^{-6}$ of the applied field.