Ferromagnetic Fe/Ag-GaAs waveguide structures for wideband microwave integrated notch filter devices

Summary form only given. Wideband electronically tunable microwave notch filters were fabricated in both flip-chip and integrated forms using Fe/Ag-GaAs waveguide layer structures. We study the coupling between the microwave electromagnetic field and the spin excitations in the ultrathin ferromagnetic Fe film. Maximum coupling and thus strong attenuation of the microwave power occur at the ferromagnetic resonance (FMR) frequency f/sub res/ of Fe, as determined by the applied magnetic fields. The peak absorption carrier frequency of a propagating microwave has been tuned in a range from 10.6 to 36 GHz in a modest magnetic field from O to 4700 Oe for the easy axis case of the Fe film. For the case of the hard axis, peak absorption tuned range is from 6 to 22 GHz. The experimental results are in good agreement with the theoretical prediction for the cases in which the magnetic fields are applied along both the easy and hard axes of the Fe film. As this type of magnetostatic wave (MSW)-based device has well-defined magnetic properties, as well as favorable electrical properties, it is desirable to incorporate them in a compound semiconductor system, in order to achieve integration into microwave integrated circuits. Also, due to the high saturation magnetization of Fe films, it is much easier to achieve higher device operating frequencies under much lower applied magnetic fields compared to previous reports on ferromagnetic yttrium iron garnet (YIG)-based devices.