Current Control Of Spin Waves In An Optic-fiber-like Magnonic Waveguide

As the information carrier of the magnon device,the spin wave has the advantages of low energy loss and easy miniaturization of the magnon device with fast transmission speed.However,due to the energy dissipation for spin-wave scattering and damping when spin waves propagated along the waveguide,the amplitude of the spin wave transmitted from the source is gradually reduced,which fatally affects the development of magnon devices.Therefore,it is necessary to find a way to compensate for the energy loss which is caused by damping.This paper combines theory and micromagnetic simulation to study the effect of current control spin waves along Neel domain wall by spin-orbit torque.Both theory and simulation show that although the dynamics of the system are complex,current can still modulate such spin waves with the help of spin-orbit torque.Unlike the spin wave in a magnon waveguide with a uniform magnetization configuration,when current is applied,the spin waves propagating along the domain wall will have peaks and troughs shifted and be amplified.The working current density of the spin-wave amplification in the system is very attractive on the order of 1010 Am-2,which has bright application prospects in large-scale electronic devices based on domain walls.This paper mainly includes the following research contents:1.We introduce the research background and clarify the significance of using the spin-Hall effect to regulate the spin wave in the domain wall-based magnon waveguide.2.In this article,we theoretically study the control of the spin wave attenuation in the domain wall by the current.By changing the ratio of field-like torque and damping-like torque of the spin-orbit torque,the influence of this change on the spin wave amplitude is obtained.By function fitting the ground state magnetization configuration,the function relationship of the small amplitude spin wave in the domain wall is obtained.It shows that the contribution of field-like torque to the spin wave amplitude is minimal,so we obtain a simplified form of the contribution of spin-orbit torque.At the same time,the ground state magnetization configuration can affect the decay length of the spin wave,which can't be ignored.Finally,by solving the LLG equation,we obtain the theoretical relationship of the spin-wave decay length.From this relationship,we can roughly grasp the key to the current regulation of the spin wave in the domain wall.3.A magnon waveguide based on a Neel domain wall is designed to realize the propagation of the spin wave and current control.By changing the size and direction of the current density,the attenuation modulation of the spin wave in the domain wall is realized.we find when we change the direction of the current density,the spin-wave attenuation can be compensated or accelerated,and also the constant amplitude propagation or amplification of the spin wave can be achieved by changing the size of the current density.At the same time,the dispersion relationship of the spin wave in the domain wall under different current densities is obtained.4.The mechanism of how the spin-orbit torque regulates the spin-wave amplification and acceleration attenuation in the domain wall is studied,and the reasons for the amplification and displacement of the spin-wave peaks and troughs are studied.