In-Plane Magnetic Anisotropy Regulation And Planar Hall Effect In Heavy Metal/Ferromagnetic/Oxide Structure

Magnetic Random Access Memory(MRAM)has attracted wide attention due to its advantages of low static power consumption,non-volatile and fast reading and writing speed.The recent researches focus on how to control the magnetization reversal of the free layer magnetic moment by the spin orbit torque excited by in-plane current.However,because the interface microstructure,magnetic anisotropy and other related parameters would affect the spin orbit torque,there is a lack of sufficient understanding about the influence of interface on spin orbit torque,especially Rashba effect,in magnetization reversal and other related physical mechanism.The structure of in-plane magnetic anisotropy could control the in-plane magnetic anisotropy,coercivity and orientation of easy magnetization axis.Furthermore,by means of the angle dependence of planar Hall effect,the effect of the direction of current,the direction of magnetization,external magnetic field and Rashba effect on the in-plane current induced magnetization reversal.And meanwhile,the structure of in-plane magnetic anisotropy is regarded as an ideal carrier to study the physical mechanism of spin orbital torque.In this paper,the samples of Ta/Fe80Ni20-O/Al2O3 and Ta/Co20Fe60B20/MgO multilayer films with in-plane uniaxial magnetic anisotropy were prepared by magnetron sputtering technology.The influence of oxide type,ferromagnetic layer thickness,and oblique angle on the in-plane magnetic anisotropy of samples were studied.Furthermore,the effect of the current and the direction of the applied magnetic field on the plane Hall effect were systematically studied.The main contents are as follows:(1)The structure of Ta/Fe80Ni20-O/Al2O3 with different in-plane uniaxial magnetic anisotropy were prepared by oblique sputtering.The magnetic characteristics of the inplane and vertical directions of these samples were systematically studied by the Vibrating Sample Magnetometer(VSM).It is found that all the samples have good inplane uniaxial magnetic anisotropy,the magnitude of the in-plane magnetic anisotropy field could be adjusted in the range of 50-120 Oe,when the thickness of Fe80Ni20-O layer is in the range of 10-30 nm;Besides,the magnetic properties of the sample could also be adjusted by changing the angle of oblique sputtering.The magnitude of the inplane uniaxial magnetic anisotropy enhances as the oblique sputtering angle increased,the magnitude of the anisotropic field could be regulated in the range of 30-80 Oe by changing the angle of oblique sputtering.(2)The samples of Ta/Co20Fe60B20/MgO with in-plane uniaxial magnetic anisotropy were prepared by magnetron sputtering.The in-plane uniaxial magnetic anisotropy was exhibited only when the oblique sputtering angle is 33°,which is different from the samples of Ta/Fe80Ni20-O/Al2O3.Moreover,the magnitude of the inplane magnetic anisotropy field gradually increased as the thickness of the Co20Fe60B20 layer increased and the magnitude of the in-plane magnetic anisotropy field could be regulated within the range of 90-230 Oe by changing the thickness of the magnetic layer.(3)Using the Physical Property Measurement System(PPMS)horizontal rotating rod,the effect of the magnitude and direction of the current and the applied magnetic field on the planar Hall effect was systematically studied.Besides,the angular dependence between the magnetization process and the in-plane magnetic anisotropy field was studied by the planar Hall effect.The results show that the magnetization process was determined by the energy competition between the external magnetic field and the in-plane magnetic anisotropy field.