The Enhancement Of Spin-orbit Torque Efficiency And The Regulation Of DM Interaction In The Multilayer Of PtCr Alloy

The spin polarized current generated by the current flowing through the heavy metal layer with spin orbit coupling acts on the adjacent ferromagnetic layer to make the magnetization switching,which find a new route for the development of the new generation of magnetic dynamic random storage.This paper mainly introduces the mechanism and process of spin-orbit torque(SOT)driven magnetization reversal in magnetic random storage.It also includes a brief introduction of some knowledge about magnetic interaction,magnetic structure and spintronics,which play an important role in the process of magnetization reversal.In order to improve the utilization of energy,all researchers have been pursuing the goal-the efficiency of SOT devices.In addition,Dzyaloshinskii-Moriya(DM)interaction is the fundamental factor for maintaining domain wall chirality for Neel domain wall against external influence.The domain with larger DM interaction is more stable and faster in migration.The smaller DM interaction is,the smaller the requirement of in-plane magnetic field to break chirality is when SOT drives magnetization reversal.Therefore,designing a device with adjustable DM interaction is of great significance.Based on the current situation,the following research has been done:In order to study the oscillation phenomenon of interlayer exchange coupling,Co and TbCo multilayers were prepared by magnetron sputtering equipment,and the interlayer exchange coupling was studied.By changing the composition of TbCo artificial ferromagnetic structure,the exchange field of Co layers on both sides of Ru in ferromagnetic coupling state was successfully observed.The experimental results show that with the increase of Ru thickness,the system presents a typical oscillatory coupling phenomenon,and the coupling strength decreases gradually.This method can be used to explore multilayer systems with more complex coupling conditions.In the Pt100-xCrx/Co/AlOy system with perpendicular magnetic anisotropy(PMA),Cr was doped into Pt to improve the efficiency of SOT and DM interaction.With increasing the Cr content of PtCr alloy to about 25%,the efficiency of SOT is the highest,which is almost twice that of pure Pt.Components corresponding to maximum efficiency of PtCr alloy is almost the same as that of PtAu alloy and PtPd alloy.It shows that it may be only pure doping effect.The DM interaction constant D increases from 0%to 25%and decreases from 25%to 50%.Combined with the variation of magnetic properties of PtCr alloy with composition,it shows that the ferromagnetic coupling tends to increase D and the antiferromagnetic coupling tends to decrease D.It is found that the absolute values of SOT efficiency and D increase with the increase of the thickness of the PtCr alloy layer,indicating that the alloy layer must be thick enough to achieve the maximum SOT efficiency and DM interaction.