Coupled Spin-wave Functional Devices

The contradiction between low power consumption and high integration limits the development of integrated circuits.Traditional charge-transportation based CMOS technology has hit a bottleneck.Owing to the properties of short wave length and ultra-low power consumption,spin waves are considered as one of the most competitive information carriers in next generation.Due to the nature of fluctuation based operation,spin-wave based information processing devices are considered that they are not only expected to realize the traditional Boolean logic operations of parallel processing of multi-channel data,but also may be applied to non-Boolean logic operations such as artificial neural networks and other fields.Among the many spin-wave based information processing devices,due to their potential applications as efficient and controllable connections between other spin-wave functional devices,the study of coupled spin-wave functional devices has become a research hotspot in the community.In this thesis,based on the review and analysis of the current developments of coupled spin-wave functional devices,in view of the shortcomings of current function switching methods of reconfigurable spin-wave directional couplers,we propose to utilize the current-induced spin-orbit torque?SOT?to achieve the dynamic switch of the function and the operating frequency of spin-wave directional couplers.The main research work includes:The basic working principle of spin-wave directional couplers was studied using theoretical analysis and micromagnetic simulation methods.The influence of the switch of the relative magnetization configuration of the spin-wave directional coupler on the coupling efficiency of the device was investigated.Using micromagnetic simulation,a reconfigurable spin-wave directional coupler model based on the magnetization configuration switch utilizing SOT is proposed.The effects of current density and current pulse application time on the magnetization configuration switch process and results of the proposed directional coupler were systematically studied.Verification of the increase of damping coefficient and RF propagation modulation in waveguides that may occur in practical applications has been done.After in-depth research,the following results and conclusions are obtained:?1?The coupling efficiency of the spin-wave directional coupler with anti-parallel magnetization configuration is higher than that with parallel.It was further proved that the reconfigurable spin-wave directional coupler can be realized by using the switch of the magnetization configuration.?2?The optimal current density required to switch the magnetization state is determined to be J=12×10¹¹ A/m²,and the optimal current pulse application time is determined to be 86 ns.By switching all or part of the magnetization state,dual dynamic reconstruction of the function and operating frequency of the proposed directional coupler is achieved.?3?Aiming at the problem of the magnetic domain wall movement in the proposed directional coupler when it is used for a long time in practical applications,a solution to introduce patterned notches on the side of the waveguide is proposed.?4?Aiming at the post-processing of a large number of micromagnetic simulation data,a set of multi-type Fourier analysis software accelerated by multi-processsing technology was developed,which can effectively decrease the calculation time and reduce the memory consumption by 2/3.The SOT-based reconfigurable spin-wave directional coupler proposed in this thesis is efficient,bias-free,and its function and operation frequency can be dynamically reconfigured.It is expected to become reliable connections between information processing units in the two-dimensional magnonic circuit in the future.