Modulation Of Spin-orbit Torque And Observation Of Domain Reversal Process

The rapid development of information technology puts higher demands on the storage density,read/write speed and stability of the memory.To meet these demanding requirements,the spin-orbit torque(SOT)has been studied in recent years.For the practical application of SOT related devices,one needs to consider the current-spin current conversion efficiency of the spin-orbit coupling layer,the perpendicular magnetic anisotropy energy of the magnetic layer,the compatibility with the semiconductor annealing process,the tunnel magnetoresistance and so on.At present,SOT research mainly focuses on how to improve the current-spin current conversion efficiency in SOT,but the compatibility with magnetic tunnel junctions is not enough.In addition,the study of Dzyaloshinskii-Moriya interaction(DMI),the dynamic process of magnetic doma:in inversion and the efficient regulation of them are also important for the realization of high-speed and high-density track memories and SOT devices without external field assistance.Based on the research status of SOT,this paper studied SOT in heavy metal/ferromagnetic layer/oxidation layer and effectively modificating it.(1)A scheme of using a Ta/W composite heavy metal layer as a spin-orbit coupling layer of an SOT device is proposed.Ta/W/CoFeB/MgO multilayer film was prepared which not only has good heat resistance,high perpendicular magnetic anisotropy,but also has an effective spin Hall angle of up to 0.5.This scheme makes full use of the advantages of Ta/CoFeB/MgO and heavy metal W,which enhances the SOT efficiency and magnetic properties of the multilayer film,and provides an effective way for the practical application of SOT devices.(2)Achieving the goal of regulating the SOT effect based on the interface effect.There are many interface-related effects in heavy metal/ferromagnetic/oxide multilayer films,such as per:pendicular magnetic anisotropy,spin pass rate,DMI,etc.,all of which are closely related to SOT devices.We introduce ultra-thin W intercalation in Ta/CoFeB and NiO intercalation in Pt/CoFe.Both intercalation layers increase the spin Hall angle of the system and reduce the external field required for current-induced magnetization reversal.Finally,the dynamic process of magnetic domain inversion is observed.It is pointed out that the magnetic domain inversion process is related to the interaction of the auxiliary external field and the DM equivalent field.Our experimental results reveal the effectiveness of SOT based on interfacial effects.For the first time,the magnetization reversal of MgO/CoFeB/MgO is realized,which provides an experimental basis for the effective combination of SOT and the high-density magnetic tunnel.