High spin-wave propagation length consistent with low damping in a metallic ferromagnet.

Abstract

We report ultralow intrinsic magnetic damping in Co₂₅Fe₇₅ heterostructures, reaching the low 10^-4 regime at room temperature. By using a broadband ferromagnetic resonance technique in out-of-plane geometry, we extracted the dynamic magnetic properties of several Co₂₅Fe_75-based heterostructures with varying ferromagnetic layer thicknesses. By measuring radiative damping and spin pumping effects, we found the intrinsic damping of a 26 nm thick sample to be <i>α</i> ₀ ≲ 3.18 × 10^-4. Furthermore, using Brillouin light scattering microscopy, we measured spin-wave propagation lengths of up to (21 ± 1) <i>μ</i>m in a 26 nm thick Co₂₅Fe₇₅ heterostructure at room temperature, which is in excellent agreement with the measured damping.