Micromagnetic simulations on demagnetization processes in anisotropic Nd2Fe14B magnets

Abstract

Abstract Individual grains with diverse dimensional parameters were introduced to investigate the magnetization reversals in anisotropic Nd2Fe14B magnets. The micromagnetic simulations were carried out via Object Oriented MicroMagnetic Framework (OOMMF). With the same bottom area and height, analysis results show that the coercive fields for different bottom shapes are of similar values. Designed as a cubic grain, the coercive field presents descending tendency as grain volume ascends. Under constant grain volume, with aspect ratio increasing, the coercive field decreases in the beginning and increases soon. Based on the demagnetization field vector, the effects of bottom shape, grain volume and aspect ratio on the coercive field can be explained. The nucleation point is chosen to discuss. Its synthetic field and reversal field are calculated by parallelogram law and inverse external field equation, respectively. The synthetic field equal to the reversal field is defined as critical field, which always shows the same tendency as the coercive field for all cases of this study. It can be concluded that critical field is qualified to be a reference index to measure the magnitude of coercive field.