Study On The Coupling Between Magnon And Magnon In Magnetic Multilayers

The collective motion mode of spin in a magnetically ordered system is called spin wave.As quasiparticle of spin waves,magnon can be coupled with photon,phonon or magnon through various interactions.Among them,the coupling between different magnon and magnon modes through interlayer exchange interaction in magnetic multilayer structures has been widely studied.Ferromagnetic resonance(FMR),as the ground state magnon mode,is expected to achieve stronger magnon-magnon coupling in FMR and FMR systems.Based on interlayer exchange interaction and two-state model,the independent FMR and the dispersion crossover of the two ferromagnetic(FM)layers are the necessary prerequisites to realize the coupling.In this paper,the FMR dispersion crossover of Co Zr and Fe Ni magnetic layers is realized by adjusting magnetic anisotropy and thickness by oblique sputtering technology,and the strong FMR-FMR coupling is realized by interlayer exchange interaction.The strong coupling phenomena in Co Zr/Fe Ni bilayer film system and Co Zr/Ta/Fe Ni trilayer film system are studied respectively,and the coupling strength,coupling field and coupling efficiency are adjusted.The main work completed and innovative conclusions are as follows:1.In the CoZr/FeNi bilayer film system,the strong coupling between the same ground state magnon modes is realized.By adjusting the thickness and anisotropy of FM layers,the independent FMR of two FM layers is obtained by oblique sputtering technology.When the external magnetic field is along the hard axis(HA)of samples,the FMR-FMR coupling due to interlayer exchange interaction is observed by ferromagnetic resonance spectroscopy.Based on the two-state model,it is found that the coupling strength reaches 0.4 GHz,the coupling efficiency reaches 6.9 %,and the strong FMR-FMR coupling is realized.2.In the CoZr/Ta/FeNi trilayer film system,the coupling strength is adjusted by the inverse relationship between the coupling strength and the thickness of the nonmagnetic(NM)interlayer.Based on the positive correlation between the coupling strength and the amplitude of the interlayer exchange interaction,the inverse relationship between the amplitude of the interlayer exchange interaction and the thickness of the NM layer,the coupling strength between FMR and FMR is changed from 0.56 GHz to 0.1 GHz by changing the thickness of the Ta layer,and the coupling phenomenon between FMR and FMR disappears when the Ta layer is thick enough.3.In the CoZr/Ta/FeNi three-layer film system,the coupling between FMR and perpendicular standing spin wave(PSSWs)is realized by changing the magnetic field configuration.When the external magnetic field is along easy axis(EA)of samples,the FMR dispersion of the Co Zr layer crosses with the 1st PSSW dispersion of the Fe Ni layer,and the magnon-magnon coupling between the FMR and PSSWs of different layers are realized.By changing the oblique sputtering angle of samples,the coupling field and coupling efficiency are adjusted.