Study On The Optical Mode Resonance Control Of FeCoB/Ru/FeCoB Triple-layer Films With Interlayer Exchange Couplin

With the development of electronic components in the direction of miniaturization,integration,low energy consumption and high frequency bands,the requirements for supporting materials are also increasing.For soft magnetic materials,the thin film morphology with in-plane uniaxial magnetic anisotropy can effectively break through the Snoek limit,so they are more suitable for applications in high frequency field above GHz.In recent years,due to the high optical mode ferromagnetic resonance frequency and relatively high magnetic permeability in the interlayer exchange coupled multilayer films,they have been widely used in microwave devices,and research in this area has also received extensive attention.In this paper,trilayers with interlayer exchange coupling are taken as the research object.A series of works have been carried out on the effect of interlayer exchange coupling on optical mode ferromagnetic resonance and the regulation mechanism of optical mode.The main research contents are as follows:1.To explore the formation and regulation mechanism of optical mode ferromagnetic resonance.The FeCoB（25 nm）/Ru（3（?））/FeCoB（25 nm）trilayer films were prepared by the composition gradient sputtering method.The experimental results show that a pure optical mode ferromagnetic resonance frequency over 22 GHz is obtained along the easy axis direction due to the strong interlayer exchange coupling caused by the insertion of the ultrathin Ru spacer layer.By changing the B-doping content to change the interlayer exchange coupling strength,the optical mode ferromagnetic resonance frequency can be regulated between 13.69 GHz and 22.68 GHz.In addition,it was found that under a certain magnetic field,the ferromagnetic resonance mode of the sample can be switched to achieve a significant frequency shift exceeding 16 GHz.2.The influence of the thickness of the non-magnetic layer on the interlayer exchange coupling was explored.A series of FeCoB/Ru(t_Ru)/FeCoB trilayers with different Ru thicknesses were prepared by composition gradient sputtering.By adjusting the thickness of the intermediate layer Ru,oscillatory changes in the type of interlayer exchange coupling were observed for two cycles.This process can be divided into four parts,0-2,2-8,9-14.5and above 16（?）,corresponding to ferromagnetic coupling,antiferromagnetic coupling,ferromagnetic coupling and antiferromagnetic coupling,respectively.In addition,in the first antiferromagnetic coupling region of the interlayer thickness t_Ru=2-8（?）,the optical mode ferromagnetic resonance frequency is larger than the acoustic mode ferromagnetic resonance frequency.And when the thickness of the interlayer is 2.5（?）and the coupling strength is-4.62 erg/cm²,the optical mode ferromagnetic resonance frequency is 20.02 GHz,which means that antiferromagnetic coupling is an effective way to increase the ferromagnetic resonance frequency.3.The FeCoB/Ru/FeCoB/PMN-PT trilayers were regulated by electric field by piezoelectric strain,and the mechanism of electric field regulated ferromagnetic resonance steering of optical mode was discussed.The results show that the optical mode resonance can achieve 90°reversible rotation under the action of the applied electric field.Since the interlayer exchange coupling is not destroyed by piezoelectric strain,the advantage of ultra-high optical mode resonance frequency in the trilayers is retained.The competition between the composition gradient sputtering induced anisotropy and the piezoelectric strain induced tunable anisotropy changes the magnetic configuration thereby producing a controlled rotation of the optical mode resonance.Moreover,the electric field regulation of the optical mode resonance has good reversibility and repeatability.This repeatability of electric field manipulation paves an effective way to design functional devices.