Microwave Photon Generation by Thin Magnetic Films

Abstract : The magnetostrictive generation of microwave phonons by thin magnetic films is theoretically described and experimental data taken at X-band are discussed. The cases of generation on the uniform precession on ferromagnetic resonance (FMR) and on spin-wave resonance (SPWR) are treated. Wave equations are obtained for the displacement components when the dc magnetic field makes an arbitrary angle with the film normal. These have driving terms proportional to dm/dy which are responsible for the phonon generation. It is shown that in the FMR case the generation occurs at the film surfaces, while in the SPWR case the generation takes place throughout the film interior. The experimental data appear to support the generation model in the FMR case, but unexplained discrepancies exist between theory and experiment in the SPWR case. A comparison with quartz piezoelectric generation is made, and while the generation efficiencies are about equal, substantial improvement is possible in the magnetostrictive case.