Soft Magnetism, Magnetostriction, and Microwave Properties of Fe-Ga-C Alloy Films

A systematic investigation of the soft magnetism, the change of modulus of elasticity with magnetization (ΔE effect), magnetostriction, and microwave properties has been carried out on iron-gallium-carbon thin films over a wide carbon content range. The phase transformation of the Fe-Ga-C films from bcc polycrystalline to amorphous leads to excellent magnetic softness with a low coercivity of less than 1 Oe, high saturation magnetization, narrow ferromagnetic resonance linewidth at 10 GHz of 20 to 30 Oe, and an ultra-low Gilbert damping constant of 0.0027. A record high piezomagnetic coefficient of 9.71 ppm/Oe, high saturation magnetostriction constant of 81.2 ppm, and large ΔE effect of -120 GPa at 500 nm were achieved.