Research On Spin-Orbit Torque And High Frequency Magnetization Dynamics Of Magnetic Heterostructures

Spintronics is an emerging discipline that explores how to control and utilize the spin property of electrons to realize new electronic devices and technologies.Specifically,using electrical methods to manipulate the magnetization is one of the most important topics in this field.At present,utilizing the spin-orbit torque（SOT）generated by spin-orbit coupling in materials to control the magnetization is the most promising research direction in spintronics.This article focuses on the SOTs,by establishing a ferromagnetic resonance measurement system and integrating high-frequency magnetization dynamics characterization methods,innovative work has been made in three aspects,including SOT dynamics characterization methods,spin transport models,and SOT related new materials.The specific research contents are as follows:（1）By analyzing the physical mechanisms of spin torque ferromagnetic resonance（ST-FMR）and spin pumping（SP）characterization techniques,the contribution of SP in ST-FMR due to the combined effect of SOTs and Oersted field was thoroughly investigated,and theoretical corrections were made to ST-FMR technique.ST-FMR and SP measurements were realized in a self-developed room temperature ferromagnetic resonance measurement system.The SOT efficiency of the Pt/NiO/Py(Ni₈₁Fe₁₉)system was characterized using SP assisted ST-FMR to obtain more accurate SOT efficiencies of the system.Then the SOT efficiency of the Pt/NiO/Py system improved by the insertion of thin layer NiO was confirmed.Meanwhile,the changes in SOT efficiency in the system further confirm the reliability of the theoretical correction of ST-FMR.（2）The magnon-mediated spin transport in the YIG layer was studied in the Pt/YIG/Py system.By optimizing the growth conditions of Pt/YIG bilayer and the heterostructure fabrication process,we realized the detection of spin transport in Pt/YIG/Py system,where spin injection from the Py layer is mediated by magnons in the YIG layer.Additionally,we established a transport model that includes the spin-magnon conversion mechanism at the Pt/YIG interface to analyze the transport properties of the system.（3）The enhancement of spin Hall effect at low temperature caused by topological band structure in magnetic two-dimensional material Fe₃GeTe₂（FGT）was investigated.High-quality FGT heterostructure samples（Tc～210 K）were prepared,and the temperature-dependent ST-FMR was utilized to characterize the FGT/Mg O/Py system and compare the SOT efficiency of the control samples,confirming the significant enhancement of SOT in FGT at low temperature.In addition,we demonstrated the magnetization switching of CoFeB with perpendicular magnetic anisotropy driven by current induced SOT in the FGT layer.