# High Spin-Wave Propagation Length Consistent with Low Damping in a Metallic Ferromagnet

## TL;DR

This study demonstrates ultra-low magnetic damping and long spin-wave propagation lengths in Co25Fe75 heterostructures at room temperature, highlighting their potential for magnonic applications.

## Contribution

It provides the first comprehensive measurement of intrinsic damping and spin-wave propagation lengths in Co25Fe75 at room temperature, confirming their suitability for low-loss magnonic devices.

## Key findings

- Intrinsic damping as low as 3.18×10⁻⁴ in 26 nm Co25Fe75
- Spin-wave propagation length of approximately 21 μm at room temperature
- Excellent agreement between damping measurements and spin-wave propagation lengths

## Abstract

We report ultra-low intrinsic magnetic damping in Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructures, reaching the low $10^{-4}$ regime at room temperature. By using a broadband ferromagnetic resonance technique, we extracted the dynamic magnetic properties of several Co$_{\text{25}}$Fe$_{\text{75}}$-based heterostructures with varying ferromagnetic layer thickness. By estimating the eddy current contribution to damping, measuring radiative damping and spin pumping effects, we found the intrinsic damping of a 26\,nm thick sample to be $$\alpha_{\mathrm{0}} \lesssim 3.18\times10^{-4}$. Furthermore, using Brillouin light scattering microscopy we measured spin-wave propagation lengths of up to $(21\pm1)\,\mathrm{\mu m}$ in a 26 nm thick Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructure at room temperature, which is in excellent agreement with the measured damping.