Dependence of coercivity on length ratios in sub-micron Nd 2Fe14B particles with rectangular prism shape

Demagnetization curves of sub-micron Nd2Fe14B particles with rectangular prism shapes were simulated by micromagnetic simulations. Coercivity decreases with increasing particle thickness for same particle volumes. This unexpected behavior can be explained by different resulting angles of the total effective field when superimposing the applied field vector with the stray field vector at the point of the first reversal event. The angular dependence of the nucleation field follows a Stoner-Wohlfarth like behavior.