The Study Of Spin Hall Magnetoresistance In Pt/[CoNi]_n Multilayers Heterostructure

Spin current,coming from the directional transport of non-equilibrium spin angular momentum,is an important medium to construct a new generation of information storage and processing devices.The generation and detection of spin current,spin dependent transport and the interaction between spin and local magnetic moment in magnetic heterostructures,are the focus of attention in spintronics.Spin Hall magnetoresistance is a new magnetic transport phenomenon caused by the anisotropic absorption of spin currents by local magnetic moments in magnetic heterostructures.Because of its convenient experiment,simple principle,and comprehensive reflection of spin current related properties,it has become an effective method to study spintronics in magnetic heterostructures.Although spin Hall magnetoresistance was first proposed in magnetic insulator heterojunctions,spintronics devices using spin-dependent effects are mainly based on metallic materials at present.Therefore,the spin Hall magnetoresistance in all-metallic heterostructures has received extensive attention in recent years.However,due to other related properties of ferromagnetic metals,SMR becomes very complicated.So it is important to develop and explore new methods to study SMR in all metal heterostructures for further understanding of spin transport and its mechanism,promoting the potential application of information recording and processing devices based on spin current.In this paper,we have effectively separated bulk and interface contribution in Pt/[CoNi]_nmultilayers based on the interfacial characteristics of SMR,realizing the direct characterization of SMR.In addition,combining with another set of independent characterization techniques and verifying each other,we carried out the spin torque ferromagnetic resonance in this system.The main conclusions are as follows:a)The experimental results of magnetoresistance measurement indicate that the contribution of the interfacial magnetoresistance in the plane perpendicular to the current does not include SMR.The direct measurement of SMR from that plane is no longer applicable to metal magnetic heterostructures and the effect of ferromagnets on spin transport needs to be carefully considered.b)According to the results of spin torque ferromagnetic resonance,it is found that the generation of spin current and spin orbit torque in metal heterostructures have no necessary relationship with the SMR.Combined with the Elliott-Yafet mechanism,this phenomenon is qualitatively explained based on the spin scattering mechanism in ferromagnets.