Fast Micromagnetic Simulation of Vortex Core Motion by GPU

Micromagnetic simulation has been used to calculate magnetization distribution and dynamics in nanoscale magnetic materials. A method reducing the calculation time is needed because it requires prolonged periods for calculation. We propose a method of calculation to reduce the calculation time with a graphics processing unit (GPU). The speed with the proposed method is fifteen times faster than that with the conventional one with a CPU at maximum. Because a GPU has very fast single precision calculation units and relatively slow double precision calculation units, it is necessary to use single precision units for fast calculation with a GPU. The difference between the results of one calculation with single and double precision units is very small. However, this difference accumulates in simulations. There is a possibility the results may change due to this difference. This effect is investigated with static and dynamic simulations with a vortex structure in a nanodot. The relative differences in static and dynamic calculations are 10-6 and 0.04, respectively. These differences are sufficiently small for practical simulations. Therefore, a method with a GPU is useful to obtain micromagnetic simulations of vortex core motion.