High Frequency Magnetic Properties Of Co-Based Soft Magnetic Thin Films

The development of science and technology has put forward higher and higher demands on the high frequency properties of soft magnetic materials.In order to meet the requirement of high-frequency applications,soft magnetic materials must have high magnetic permeability and high cut-off frequency.Therefore,this thesis takes cobaltbased soft magnetic thin films as the research object,starts from high frequency theories,and focuses on the control of high frequency magnetic properties.A series of related research has been carried out.The main innovative results are as follows:1.High magnetic permeability of the hundred order and natural resonance frequency of GHz has been realized in the Co-Zr(Cobalt-Zirconium alloys)thin films.By combining doping and oblique sputtering methods,the in-plane uniaxial anisotropy has been controlled in a wide range.The effective anisotropy magnetic field is tuned in the range of 19.8 to 517.5 Oe,and the natural resonance frequency reaches up to 7.1GHz.2.The magnetic anisotropy induced by oblique sputtering originates from the microstructural anisotropy due to the self-shadowing effect.With the increase of incidence angle,the effective anisotropy magnetic field of Co-Zr thin films first increases and then decreases.As the sputtering pressure decreases,the maximum value of the effective anisotropy magnetic field appears at higher oblique sputtering angle.3.The anisotropy of damping factor in Co-Zr films has been found.The ferromagnetic resonance linewidth of the system is analyzed by using the spin rectification effect.The contributions of the intrinsic linewidth,four-fold symmetrical non-uniform linewidth and two-magnon scattering linewidth have been separated.The results show that there is a jump in the two-magnon scattering linewidth near the 60°incidence angle,which also originates from the anisotropy of the microstructure.4.Retuning of in-plane uniaxial anisotropy of Co-Zr thin films has been realized.In the Co-Zr/PMN-PT heterojunction,not only the strength of the anisotropy can be regulated,but also the direction of the anisotropy can be regulated.The maximum stress anisotropy magnetic field in the [011] direction of PMN-PT is 25.4 Oe.There is a loop response of the resonance field with the electric field,which proves that there is a charge regulation mechanism at the interface of the Co-Zr/PMN-PT heterojunction.