Study Of Nano-ring MTJs Based Spintronic Devices And Spin Transport Properties In N-doped Silicon

With the deepening of information technology revolution and the development of large-scale integrated circuits,spintronic devices have attracted more attentions due to their unique electron spin degrees of freedom,good compatibility with existing semiconductor processes,low power consumption,thermal stability and the advantages of higher signal-to-noise ratio.It is considered to be one of the most promising hightech industries that are most likely to break the limits of Moore's Law.How to control the spin in these devices has become a hot research direction.In this thesis,we take " Study of nano-ring MTJs based spintronic devices and spin transport properties in ndoped silicon " as the topic.By fully combining the current studies on the detection of spin currents in magnetic multilayers and spin-electronic devices based on magnetic tunnel junctions,we hope to look for and explore new ways to regulate electron spins.This thesis is divided into three parts:(1)Based on the magnetic multilayers with core structure of Co Fe B/Mg O/Co Fe B,the ring-shaped magnetic tunnel junctions with the size of ~100 nm are fabricated.By applying DC current vertically under zero magnetic field,the spin transfer torque induced magnetization switching in the free layer is achieved,which is utilized as the prototype device for the second-generation magnetic random access memory.Also,by increasing the current amplitude,the magnetization backhopping is observed.Based on that,a true physical random number generator is demonstrated.(2)By integrating the above nano-ring magnetic tunnel junctions in the coplanar waveguide,the spin transfer torque ferromagnetic resonance is launched under the ac current in the frequency of gigahertz range.We have found that in the case of steady precession with just the free layer magnetization,the mutually independent acoustic-like and optical-like resonance modes are observed simultaneously in a given magnetic field.This result is explained from the perspective of micromagnetic simulation and quantitatively theoretical analysis.It turns out that the existance of the two borders of the ring shape provides the limits to the propogation of the spin waves,resulting in standing spin waves,which further leads to the in-phase and anti-phase resonance modes.Based on this study,the dual-mode microwave detector is proposed,with the advantage of the double microwave frequency detection simutaineously under a given magnetic field,which significantly improves the detecting efficiency.(3)By utilizing the new wafer-bonding technique,the problem of the inhibition of direct deposition for silicon films is solved.Based on that,we successfully insert the n doped silicon thin film in between the ferromagnetic layer and heavy metal layer by forming the vertical structure of Co Fe B/Mg O/n-Si/Pt.By exciting the ferromagnetic resonance in the Co Fe B,according to the spin pumping theory,the pure spin current is pumped into and penetrates the n-Si layer,and finally is detected by Pt layer via the inverse spin Hall effect.As a result,the pure spin diffusion length in n-Si without the scattering of the surface(compared with the laterial structure)is detected to be 2.0 ?m,almost doubled compared with previous studies.This research has important guiding significance for the study of spin current diffusion in semiconductors.