Research On High-frequency Soft Magnetic Properties Of FeCo-based Film

Due to the rapid development of integrated circuit technology,higher requirements have been put forward for ferromagnetic resonance RF microwave devices in various fields.High frequency soft magnetic film materials under the condition of self-bias have become an indispensable material.At the same time,with the further development of the Internet and flexible intelligent devices that can be folded and bent,it has become an irresistible trend to realize the flexibility of traditional functional materials.On the basis of meeting the high frequency resonance,magnetic materials also need to have the advantages of higher sensitivity,better ductibility and better mechanical properties.Therefore,it is particularly important to study the high frequency and ductility of magnetostrictive materials.Taking FeCo material as the research object,this paper focuses on the formation and regulation mechanism of optical film in FeCo based magnetic anisotropic single-layer film and FeCoB/Ru/FeCoB three-layer film to study the influence of different fields on improving the resonance frequency of soft magnetic film.The main research contents are as follows:（1）Study the influence of stress field in flexible substrate and buffer layer on magnetic properties of FeCoB/Ru/FeCoB three-layer soft magnetic film.The three layers of FeCoB/Ru/FeCoB films（the thickness of the middle layer is 3（?））were prepared by inclined sputtering and component gradient sputtering.Compared with the rigid substrate,the ferromagnetic resonance of the three layers of films grown on the flexible substrate showed obvious enhancement.The influence of 5 nm buffer layer Ta on the magnetic properties of FeCoB/Ru/FeCoB three-layer soft magnetic film was investigated.The experimental results show that the buffer layer Ta can relieve the stress in the substrate and improve the strength of the resonant peak of the soft magnetic film.（2）Study the influence of applied magnetic field direction on magnetic properties of FeCoB/Ru/FeCoB three-layer film on rigid substrate.The experimental results show that the soft magnetic film changes from uniaxial anisotropy to biaxial anisotropy by applying an external magnetic field parallel to the easy axis of the soft magnetic film during the heat treatment process.The uniaxial anisotropy induced by the component gradient sputtering competes with the anisotropy induced by the external magnetic field,thus changing the magnetic moment distribution in the free layer and regulating the optical mode resonance.（3）Study the influence of magnetic crystal anisotropy field on the high frequency performance of FeCo films grown epitaxial on different substrates.The FeCo films are grown on Mg Al₂O₄（100）and Mg O（110）respectively,and quadrangular distortion occurs in the samples.The results show that the optical mode resonance frequency of FeCo films on different substrates increases first and then decreases with the increase of thickness.With the increase of the angular distortion,the magnetic crystal anisotropy can make the sample resonance reach extremely high frequency,and the nanocrystalline epitaxial films with optical mode resonance up to 38.2 GHz are obtained on the Mg O（110）substrate.The films obtained from the epitaxial of two crystals to the substrate have different symmetries,and the reason for this phenomenon is determined.