Micromagnetic Simulations on GPU, A Case Study: Vortex Core Switching by High-Frequency Magnetic Fields

Abstract

Abstract-Since magnetic vortex cores have two ground states, they are candidates for digital memory bits in future MRAM devices. Vortex core switching can be induced by exciting the gyrotropic eigenmode e.g. by applying cyclic magnetic fields with typically a sub-GHz frequency. However, recent studies reveal that other modes exist that can be excited at higher frequencies, but still lead to switching with relatively small field amplitudes. Here, we perform a full scan of the frequency/amplitude parameter space to explore such excitation modes. The enormous amount of simulations can only be performed in an acceptable time span when the micromagnetic (CPU-) simulations are drastically accelerated. To this aim, we developed MUMAX, a GPU based software tool that speeds up micromagnetic simulations with about two orders of magnitude compared to standard CPU micromagnetic tools. By exploiting MUMAX' numerical power we were able to explore new switching opportunities at moderate field amplitudes in the frequency range between 5 and 12 GHz.

An optimized magnetostatic field solver on GPU using open computing language

“…Micromagnetic codes in general are suitable for parallel programming as it can be easily divided into independent parts, which can run in parallel . The current trend for micromagnetic code is shifting the computationally intensive parts to GPUs.…”

Time-resolved imaging of magnetic vortex dynamics using holography with extended reference autocorrelation by linear differential operator

“…In the majority of investigations these limitations were compensated by simulation studies using micromagnetic numerical tools, such as Mumax36, from which one can further assess the effects that may not be clearly resolved in spatial imaging. This also facilitated study of the finer structure of the vortex closures and its dynamics11263738 and to investigate non-linear effects and spin-wave phenomena associated with both the excitation and the steady states of the vortex gyration. The latter are of particular importance in technological applications, where vortex core manipulation underpins their operation (e.g.…”