Correlations, disorder, and multi-magnon processes in terahertz spin dynamics of magnetic nanostructures: A first-principles investigation

TL;DR

This paper investigates how correlation effects, disorder, and multi-magnon processes influence terahertz spin dynamics in magnetic nanostructures, revealing significant electron-magnon interactions and their impact on magnon energies.

Contribution

It provides a first-principles analysis of the role of correlations and disorder in THz magnons, highlighting the importance of electron-magnon interactions beyond standard approximations.

Findings

Electron self-energy partly arises from electron-magnon interactions.

Magnon energies are significantly renormalized, matching experimental data.

A hierarchy of magnon relaxation processes is established from first principles.

Abstract

Understanding the profound impact of correlation effects and crystal imperfections is essential for an accurate description of solids. Here we study the role of correlation, disorder, and multi-magnon processes in THz magnons. Our findings reveal that a significant part of the electron self-energy, which goes beyond the adiabatic local spin density approximation, arises from the interaction between electrons and a virtual magnon gas. This interaction leads to a substantial modification of the exchange splitting and a renormalization of magnon energies, in agreement with the experimental data. We establish a quantitative hierarchy of magnon relaxation processes based on first principles.