Low Gilbert damping and linewidth in magnetostrictive FeGa thin films

Abstract Fabrication of voltage tunable high-frequency devices using magnetostrictive ferromagnet-piezoelectric hybrid structures requires materials with low damping and narrow linewidth to achieve low microwave loss. Galfenol exhibits superior magnetostriction, stability over a wide range of temperatures, and is free of rare earth elements, making it an economical and promising candidate, if the microwave losses can be minimized. We report the fabrication, structural and magnetic characterization, and study of dynamic properties of epitaxial FeGa thin films exhibiting an ultra-low residual linewidth, Δ H 0 = 13 ± 1 Oe - a requirement for low microwave loss and effective damping parameter, α eff , as low as 0.0065 - 0.0001 + 0.0005 for the 16 nm thick film. Similarly, we found α eff = 0.0039 - 0.0007 + 0.0028 and Δ H 0 = 71 ± 1 Oe for the 24 nm thick film, demonstrating its potential for applications in magnetic memory and high frequency devices.