Magnetization Dynamics Of A Single-domain Magnet Under A Spin-polarized Current With A Tilted Polarization

The magnetization dynamics of the magnetic materials is always a very important subject, and the magnetization reversal has attracted extensive attention from scientists. Because of the wide use in the magnetic storage devices, the magnetization reversal is closely related to our daily lives. Nowadays with the rapid development of the information technology, the storage density and speed of the storage are more and more difficult to meet the needs of our lives and production. The storage technology of memory with high density and speed is urgently required. But since the magnetic moment reversal of real magnetic materials is a very complicated process, we could use magnetic nanoparticles to study the magnetization switching as good guidance for practical application. In this work, we mainly investigated the magnetic nanoparticles in two aspects with theoretical analysis and micromagnetic simulation.First, we gave a description of the theory of uniaxial model of magnetic nanoparticles, including the introduction of the background and development on this field by interpreting existing references, a introduction to the Landau-Lifshitz-Gilbert(LLG) equation and the spherical coordinates form of it, and also the derivation of the LLG equation with the spin transfer torque item.Then, the analysis of magnetization dynamics of a single-domain nanomagnet under a spin-polarized current with arbitrary tilted angles in polarization was investigated by solving the Landau-Lifshitz-Gilbert-Slonczewski(LLGS) equation. The macrospin simulation showed that how the critical switching current and magnetization reversal time change with the varying tilted angles. Also, results were obtained in the simulations under two different situations where considering the Slonczewski’s spin-polarized g-function type or not, which may imply that the interaction between spin-polarized electrons and the free layer magnetization do not always promote magnetization switching.Also, the analysis of magnetization dynamics of a dual spin valve under a spin-polarized current with arbitrary tilted angles in two polarizations was investigated contrasting to the traditional spin valve. The macrospin simulation showed that how the critical switching current and magnetization reversal time change with the varying spin polarization tilted angles in dual spin valves. According to the results, the complete perpendicular configuration could be called the most consumption configuration, and the complete parallel configuration could be called the most optimal configuration in the dual spin valve. Besides that, compared to the traditional tilted spin valve, a 65% decreasing amplitude could be achieved on the critical switching current in dual spin valve.The last of the article is the conclusion. And we also give some leftover problems and outlooks.