Theory And Simulation Investigation On Transport Manipulation Of Spin Quasiparticle

Spin quasiparticles provide a route for constructing spintronic devices with superior efficiency,prolonged lifetime,and enhanced integration density,exhibiting broad application prospects.The manipulation of the transport processes of spin quasiparticles is crucial for advancing the development of spintronic devices,both in fundamental physics and applications.This thesis focuses on two types of quasiparticles in spin systems,skyrmion and magnon.By theoretical calculations and micromagnetic simulations,this thesis investigated the transport manipulation of skyrmion and magnon.The main research contents of this thesis are summarized as follows:(1)The transport behavior of skyrmions in racetrack device with local exchange bias field driven by current has been investigated.The asymmetric potential barrier of skyrmions caused by the local exchange bias field has been observed,and skyrmion racetrack device based on the local exchange bias field has been proposed.The skyrmion diode is designed in this study based on the asymmetric potential barrier of skyrmions at the exchange bias field boundary.The study found that an increase in the number of skyrmions results in a decrease in the driving current to overcome the barrier in the diode.Based on the above findings,the skyrmion neuron structure has been proposed in this study,and the fire threshold of neuron can be manipulated by adjusting the driving current.(2)The current-driven transport behavior of elliptical skyrmion has been investigated.The anisotropic driving has been discovered,and the racetrack device based on elliptical skyrmion has been proposed.By introducing uniaxial in-plane magnetic anisotropy,the skyrmion Hall angle of the elliptical skyrmion can be controlled by changing the relative angle between the driving current and the in-plane magnetic easy axis.By optimizing the in-plane magnetic anisotropy,Dzyaloshinskii-Moriya interaction,and damping constant,the angle of deviation of the current-driven skyrmion from the track can be controlled,and the transport of skyrmion with zero divergent angle can be achieved under certain conditions.Based on the above findings,a method for achieving skyrmion motion along the track without any transverse offset has been proposed in this study.(3)The dispersion and transport behavior of polarized magnons in antiferromagnetically coupled magnonic crystals have been investigated,and the magnon flatband effect has been discovered.By introducing Stokes parameters,the dispersion relation of magnons with opposite polarization modes can be clearly distinguished,and the magnon flatband effect can also be observed.By manipulating the thickness of the spinopposite magnetic sublattice in the antiferromagnetically coupling magnonic crystals,the dispersion band structures of the magnonic crystals can be optimized.Based on the above findings,magnon filtering device based on antiferromagnetically coupled magnonic crystals has been proposed in this study.(4)The transport behavior of magnons in the non-uniform temperature field has been investigated,and the refraction of magnons caused by the non-uniform temperature field has been discovered.When the magnons transport in the non-uniform temperature field,the refraction effect will be produced due to the non-uniformity of the saturation magnetization.The refraction of the magnon path arises from the change of the group velocity direction caused by the change of the wave vector caused by the non-uniform magnetization.Based on the above theory,the magnon lens based on temperature gradient has been proposed in this study,which enables the focusing of parallel magnon beams and the convergence of divergent magnon beams.