Micromagnetic Study Of Magnetic Skyrmion

Magnetic skyrmion is a topologically protected magnetization distribution.Due to its small size and low driving current density,it is considered to be a good carrier for information storage,causing extensive research.In this paper,some physical properties of magnetic skyrmion,skyrmionum,and spin waves are studied by means of micromagnetic simulation.Chapter one is about the development of spintronics and nanomagnetics,and the discovery process of skyrmion.Chapter two,we introduce the research objects of micromagnetics and the various magnetic energies considered by micromagnetics.Chapter three,we introduce the aid of providing a microwave magnetic field in a vertical spin valve structure,which is capable of rapidly producing magnetic skyrmion.Chapter four,the spin motive force effect of skyrmionum is studied,under the excitation of microwave magnetic field,skyrmionum can be used as a power generation device.Chapter five,we introduce the modulation effect of the periodic arrangement of the skyrmions and the skyrmionums on the dispersion relation of the spin wave.Chapter sixis the summary and outlook.Chapter three,we study in the microwave magnetic field to accelerate the formation of skyrmion.it is found that the time for applying the microwave magnetic filed to excite the skyrmion is significantly lower than that without the microwave magnetic field.And the energy calculation of the magnetic system knows that the ferromagnetic state is transformed into the skyrmion substate,and it is necessary to cross a barrier(nucleation energy),and the application of a microwave magnetic field can quickly cross this barrier.In the syudy,we also found that the existence of an optimal microwave frequency can make the skyrmion produce at the fastest speed.In order to explor the reasons behind this phenomenon,we studied the ferromagnetic reasonance frequency with the skyrmion as the ground stste and found that this frequency is also the ferromagnetic resonance frequency,which has certain guiding significance for the design based on the skyrmion devices.Chapter four,before studying the spin motive force effect of the skyrmionum,some scholars have studied the spin motive force effect based skyrmion.however,due to the topological charge of skyrmion,it is inevitable to introduce the 'skyrmion hall effect',which is not beneficial for stable power generation.Recently,some scholars have studied that skyrmionum can suppress the 'skyrmion hall effect',because of its zero topological charge,which is an adventage for spin batteries.Therefore,we studied the spin motive force effect based on the skyrmionym,and found that the power generation efficiency of this skyrmionum is much higer than skyrmion.Chapter five,before studying the modulation of the spin wave dispersion relation by the periodic array of skyrmion and skyrmionum,we calculated the dispersion relation of the spin wave of without skyrmion and skyrmionum,and the result is two perfect paraboloids,which is consistent with the dispersion relation of free electrons.when there are skyrmions and skyrmionum in the nano-strip,the band gap,which is the forbidden band,appears in the dispersion relation of the spin wave,and it is found that the smaller the periodic interval,the wider the band gap,which is important for the design of the spin wave filter device.