Inverse Spin Hall Effect Research In YIG/NM Heterostructure

The discovery of the giant magnetoresistance effect has greatly changed the capacity of information storage,making the study of magnetic extension-spintronics aroused.People realize that if they can freely manipulate the spin of the electrons,they will lead the next revolution in information storage and communication technology.The spin Hall effect has attracted much attention for its powerful pure spin flow generation capability.The current stage of research is to clarify the physical mechanism of the spin Hall effect and to find efficient spin flow-charge flow conversion materials,in order to apply to the actual spin electronics.Based on the existing research,this dissertation studies the spin-Hall effect of two Pt-doped system materials by spin pumping effect and inverse spin Hall effect,and extracts the spin Hall angle and spin diffusion.Furthermore,combined with intrinsic and extrinsic spin Hall effect analysis of its spin-charge flow transformation behavior.Firstly,starting from the magnetization dynamics of magnetic moment precession,phenomenological understanding of the magnetic moment precession process provides the theoretical basis for the spin-pumping effect based on the ferromagnetic resonance.The precession magnetic moment transfers angular momentum at the FM/NM interface,forms spin accumulation,and generates a spin current in the nonmagnetic layer,which manifests as an increase in the damping coefficient of the system.At present,there is no method to detect the spin current directly,and the inverse effect of the spin Hall effect provides an indirect detection method.The spin current is detected by converting the voltage signal due to the spin-orbit coupling in the non-magnetic layer.Secondly,the inverse spin Hall effect in pure Pt,PtBi alloys and Pt W alloys was investigated by the self-built FMR-ISHE test system.The spin-mixed conductance of the interface is obtained from the ferromagnetic resonance,which has a certain positive relationship with the spin-orbit coupling strength of the system.The components of ISHE contribution in the voltage signal and the AHE component contributed by the trace amount of magnetic Pt at the interface are separated,the various components contained in the ISHE voltage signal are analyzed,and the spin Hall angles and spin diffusion length are extracted according to the ISHE voltage signals of different thickness samples.Finally,the contribution of intrinsic and extrinsic spin Hall effect in the alloy system is analyzed by combining the spin Hall resistivity.In PtBi alloys,when the Bi content is less than 8%,the increased spin Hall resistivity is mainly contributed by the skew scattering of Bi impurities,and is proportional to the spin-orbit coupling strength.The spin Hall angle increases from 4.9% in pure Pt to 10% in PtBi(8%)alloys.In PtW alloys,when the W content is less than 25%,the spin injection efficiency decreases as the W concentration increases,and the spin Hall angle is reduced to 0.7%.The decrease of the spin Hall resistivity results from the opposite effect of the spin-orbit coupling of Pt and W on the same spin-direction electrons,the predominant mechanism in PtW is side-jump scattering of W impurities.