Ultralow magnetic damping of a common metallic ferromagnetic film

For most magnetic materials, ultralow damping is of key importance for spintronic and spin-orbitronic applications, but the number of materials suitable for charge-based spintronic and spin-orbitronic applications is limited because of magnon-electron scattering. However, some theoretical approaches including the breathing Fermi surface model, generalized torque correlation model, scattering theory, and linear response damping model have been presented for the quantitative calculation of transition metallic ferromagnet damping. For the Fe-Co alloy, an ultralow intrinsic damping approaching 10^-4 was first theoretically predicted using a linear response damping model by Mankovsky et al. and then experimentally observed by Schoen et al. Here, we experimentally report a damping parameter approaching 1.5 × 10^-3 for traditional fundamental iron aluminide (FeAl) soft ferromagnets that is comparable to those of 3d transition metallic ferromagnets and explain this phenomenon based on the principle of minimum electron density of states.