| Recently,the era of big data has come.The scientists are turning attention to develop a new generation of data storage devices which are less energy consuming,more efficient,and higher integration with the traditional memory gradually unable to meet people's increasing demand.Magnetic random access memory(MRAM)is increasingly subjected to people's favor.Among them,magnetic random access memory(SOT-MRAM)based on spin-orbit torque(SOT)stands out because of higher storage density,lower energy consumption,high degree of integration,and becomes a strong competitor of the next generation of universal memory.SOT-MRAM uses the tunneling magnetoresistance effect(TMR)based on magnetic tunnel junction(MTJ)to read data,and uses magnetization switching driven by spin orbit torque to write data.Therefore,in order to minimize energy consumption,we need to focus on improving the efficiency of charge current transforming into spin current.So we deposit the Pt/[Ru/Pt]n/Co/Ta samples with perpendicular magnetic anisotropy by inserting ultra-thin Ru layer into Pt,and study the SOTs induced magnetization switching.The main results are as follows:(1)The Pt/[Ru/Pt]m multilayers and Pt/[Ru/Pt]n/Co/Ta samples with perpendicular magnetic anisotropy were deposed by inserting 0.2 nm ultra-thin Ru layer into the heavy metal Pt layer using magnetron sputtering.The ultra-thin Ru layer can significantly enhance the resistivity of heavy metal Pt,while the damage to the crystal structure of Pt is tiny by this way.After that,We studied the relationship between perpendicular magnetic anisotropy field Han~0 and the number of inserted layers n,and the perpendicular magnetic anisotropy fields are large and increasing.(2)In order to evaluate the efficiency of charge current transforming into spin current,we systematically study the spin orbit torque ?SH of Pt/[Ru/Pt]n/Co/Ta samples by loop-shift method.The ?SH increases first and then decreases with the increase of n,and the maximum spin Hall angle ?SH is obtained in Pt(1.0 nm)/[Ru(0.2nm)/Pt(1.0 nm)]5/Co/Ta sample.In addition,the contribution of skew scattering to extrinsic spin Hall effect is larger than side-jump scattering in our samples by analyzing the spin Hall effect mechanism.And with the help of the in-plane auxiliary magnetic field is 5% Han~0,the SOT induced magnezation switching in Pt(1.0 nm)/[Ru(0.2nm)/Pt(1.0 nm)]5/Co/Ta sample with the critical reversal current density is 3.2×10~6A/cm~2.Finally,because of the larger ?SH and smaller ?xx of Pt(1.0 nm)/[Ru(0.2nm)/Pt(1.0 nm)]5,the energy consumption of spin current generator is lower.(3)In the end,the texture of domain walls and the motion of domain walls in Pt/[Ru/Pt]n/Co/Ta system induced by magnetic field and spin-orbit torque is systematically studied using magneto-optic Kerr microscopy.Due to the Dzyaloshinskii-Moriya interaction,the domain walls of Pt/[Ru/Pt]n/Co/Ta system are all left-handed Néel type domain walls.And the magnetic and spin orbit torgue induced by current have great influence on magnetic domain wall motion. |
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