Variable damping and coherence in a high-density magnon gas

TL;DR

This paper investigates the rapid relaxation and damping behavior of a high-density magnon gas created through parametric amplification, revealing non-standard damping dependence on the pumping field and proposing a phenomenological model.

Contribution

It introduces a new phenomenological model explaining magnon dephasing and damping dependence on parametric pumping in high-density magnon gases.

Findings

Magnon damping depends on the parametric pumping field.

Standard exponential decay models do not fit the observed damping.

A phenomenological model aligns well with experimental data.

Abstract

We report on the fast relaxation behavior of a high-density magnon gas created by a parametric amplification process. The magnon gas is probed using the technique of spin-wave packet recovery by parallel parametric pumping. Experimental results show a damping behavior which is in disagreement with both the standard model of exponential decay and with earlier observations of non-linear damping. In particular, the inherent magnon damping is found to depend upon the presence of the parametric pumping field. A phenomenological model which accounts for the dephasing of the earlier injected magnons is in good agreement with the experimental data.