Nonlinear Decay of Quantum Confined Magnons in Itinerant Ferromagnets

TL;DR

This study investigates the nonlinear decay behavior of quantum confined magnons in ultrathin Co layers, revealing mode-dependent damping mechanisms through combined experimental and computational approaches.

Contribution

It uncovers the nonlinear decay rates of quantum confined magnons and provides a quantitative explanation using density functional calculations.

Findings

Magnons exhibit nonlinear decay rates depending on mode number.

Experimental and theoretical results agree on the damping mechanism.

Insights enable tuning of spin excitation dynamics in ultrathin magnetic structures.

Abstract

Quantum confinement leads to the emergence of several magnon modes in ultrathin layered magnetic structures. We probe the lifetime of these quantum confined modes in a model system composed of three atomic layers of Co grown on different surfaces. We demonstrate that the quantum confined magnons exhibit nonlinear decay rates, which strongly depend on the mode number, in sharp contrast to what is assumed in the classical dynamics. Combining the experimental results with those of linear-response density functional calculations we provide a quantitative explanation for this nonlinear damping effect. The results provide new insights into the decay mechanism of spin excitations in ultrathin films and multilayers and pave the way for tuning the dynamical properties of such structures.