# Optical excitation of single- and multi-mode magnetization precession in Galfenol nanolayers

## TL;DR

This paper explores ultrafast optical excitation of magnetization precession in Galfenol nanolayers, revealing multiple magnon modes and record-high frequencies up to 100 GHz, with potential for THz precession detection.

## Contribution

It demonstrates the excitation of multiple magnon modes and high-frequency magnetization precession in Galfenol nanolayers, highlighting their unique magnetic properties and potential for THz applications.

## Key findings

- Detected up to 6 magnon modes in 120-nm layer
- Achieved single-mode precession at 100 GHz with low damping
- Predicted THz frequency precession in future experiments

## Abstract

We demonstrate a variety of precessional responses of the magnetization to ultrafast optical excitation in nanolayers of Galfenol (Fe,Ga), which is a ferromagnetic material with large saturation magnetization and enhanced magnetostriction. The particular properties of Galfenol, including cubic magnetic anisotropy and weak damping, allow us to detect up to 6 magnon modes in a 120-nm layer, and a single mode with effective damping ${\alpha}_{eff}$ = 0.005 and frequency up to 100 GHz in a 4-nm layer. This is the highest frequency observed to date in time-resolved experiments with metallic ferromagnets. We predict that detection of magnetization precession approaching THz frequencies should be possible with Galfenol nanolayers.