Study Of Perpendicular Anisotropy And Ferromagnetic Resonance Of Ferrimagnetic Garnet Films

The development of integrated circuits has entered the post Moore era.The feature size of devices in traditional CMOS technology is still reducing,however,its performance has almost reached the bottleneck.In addition,the energy consumption of integrated circuits has attracted more and more attention.The static power consumption caused by leakage current increases with the reduction of feature size.In order to solve the above problems,spintronic devices with the advantages of low energy consumption,nonvolatile and high storage density flourish in decades.At present,the frontier research of spintronics focuses on spin orbit torque(SOT)and surface topological states,and the ferrimagnetic garnet is one of the systems applied to these basic research,which makes the garnet film with perpendicular magnetic anisotropy have attracted the attention of researchers for decades.In this work,a bismuth doped thulium iron garnet film is studied.The specific research contents are as follows:Firstly,this work sorts out the relevant work of predecessors,establishes the scientific significance of this research,briefly introduces the outstanding achievements and frontier fields in spintronics,especially the scientific research achievements of ferrimagnetic garnet materials in recent years.Then,starting from the crystal structure of ferrimagnetic garnet,the anisotropic properties in garnet films are introduced,and the conditions of thin film ferromagnetic resonance in polar coordinates are deduced.In this thesis,bismuth-doped thulium iron garnet(Tm₂Bi Fe₅O₁₂,Tm Bi IG)films of multiple thickness having strong perpendicular magnetic anisotropic effect were fabricated on substituted Gd₃Ga₅O₁₂(s GGG)substrates by pulsed laser deposition(PLD)technique.Then,the growth process and annealing process of the films were studied.Crystallographic characterization and magnetic properties of Tm Bi IG films were investigated using high-resolution scanning transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,vibrating sample magnetometry and broadband ferromagnetic resonance(FMR)measurement,respectively.A high perpendicular anisotropic field of H_?=4445±7.5 Oe in 10 nm thick film and H_?=4582±7.7Oe in 30 nm thick film at room temperature were obtained and analyzed through out-of-plane and in-plane FMR tests and Software fitting.The value of perpendicular anisotropic field of Tm Bi IG is much larger compared with the previous work,which means the Bi³⁺ions doped are significantly improved perpendicular anisotropy.Different from the previously reported in-plane FMR spectra of thulium iron garnet,an additional resonance mode was observed in the in-plane FMR tests of films with different thicknesses.Due to the fact of the strong PMA effect in Tm Bi IG films,the Landég-factors exhibit discrepancy between in-plane and the out-of-plane magnetized.The Landég-factor of the Tm Bi IG films is much lower than that of free electrons indicating that the strong spin-orbit coupling is caused by the Tm and Bi heavy elements.The Gilbert damping factor?changes from 0.007 to 0.012 in various thicknesses Tm Bi IG films,which means Bi³⁺ions doped have no significant on ?...