Tunable high-frequency properties of flexible FeGa films with rotatable stripe domain

A comprehensive investigation of stress-induced anisotropy in 300 nm Fe₈₁Ga₁₉ (FeGa) thin films with stripe domain structures has been performed by comparing static and dynamic measurements. The formation and rotation of stripe domains under a compressive stress have been imaged by magnetic force microscopy and understood by micromagnetic simulations. A double magnetic anisotropy system, combing the stress-induced uniaxial magnetic anisotropy and the rotatable magnetic anisotropy caused by the stripe domain structure was achieved in FeGa thin films. The ferromagnetic resonance frequency of 300 nm FeGa thin films with stripe domains can be enhanced from 2.7 to 3.0 GHz without sacrificing the initial permeability. This found provides us a new approach via utilizing the double magnetic anisotropies in magnetic films with stripe domains to enhance the resonance frequency beyond the Snoek's limit and extends the application for FeGa films to flexible microwave devices.