Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets

The coercive field and angular dependence of the coercive field of single-grain Nd2Fe14B permanent magnets are computed using finite element micromagnetics. It is shown that the thickness of surface defects plays a critical role in determining the reversal process. For small defect thicknesses reversal is heavily driven by nucleation, whereas with increasing defect thickness domain wall de-pinning becomes more important. This change results in an observable shift between two wellknown behavioral models. ∗This article is published in Applied Physics Letters: S. Bance et al., “Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets”, Appl. Phys. Lett. 104, 182408 (2014); http://dx.doi.org/10.1063/1.4876451