Structural, magnetic, and frequency domain ferromagnetic resonance studies of Fe82Ga18/Al2O3(001) films lightly doped with Cu and Ag

Abstract

Fe1−xGax (x ≤ 0.27) being a crucial magnetostrictive material with potential applications in spintronics, sensors, actuators, and memory devices has been studied from the point of its structural and magnetic behavior when added with 4 at. % of Cu and Ag in place of Ga. The structural characterization confirms an A2-type disordered bcc structure with almost similar crystal growth and lattice parameters similar to that of undoped FeGa, suggesting a rather interstitial type of doping. The magnetization vs magnetic field curve has shown an enhanced Mr/Ms ratio and enhanced saturation magnetization (Ms) for Fe82Ga14Ag4 (AFG) system, which has its origin in lattice expansion. The magnetization vs temperature (MT) curve shows a kink point in both systems slightly above 300 °C in MT response, suggesting the formation of an ordered phase of FeGa. The magnetic transition temperature (Tc) as determined by the MT curve shows a considerable reduction in the AFG system, which could have originated due to Ag precipitation. A Coplanar Waveguide based Ferromagnetic Resonance with a Vector Network Analyzer as a microwave source, study has shown a relatively low magnetization damping coefficient (α) and inhomogeneous broadening (ΔHo). The magnitude of α and ΔHo are as low as 0.0093 ± 0.0005 and 137 ± 5 Oe for AFG and the same for Fe82Ga14Cu4 are determined as 0.0121 ± 0.0005 and 86 ± 5 Oe which is much smaller to that reported for polycrystalline undoped FeGa.