Tunable Microwave Filters and Phase Shifters Based on Ferromagnetic/Dielectric Multilayer Waveguides

We present theoretically microwave filters and phase shifters based on the propagation of hybrid electromagnetic-spin waves in a ferromagnetic/dielectric multilayer waveguide. It is demonstrated that some propagating modes of microwave appear in the waveguide and the number of the modes increases with increasing the number of the building blocks. Those propagating modes originate from the coupling between microwave and spin wave, associated with the collective excitations of spin motions in the whole multilayer system when the layer thickness is relatively thin. In addition, it is shown that the attenuation of microwaves and phase difference in the waveguide are tuned by the magnetic field, the ferromagnetic resonance line width, and the conductivity of ferromagnetic material. The investigations can be used in designing tunable compact bandpass filters and phase shifters of microwave. (C) 2010 The Japan Society of Applied Physics