Grain-size dependent demagnetizing factors in permanent magnets

Abstract

The coercive field of permanent magnets decreases with increasing grain size. The grain size dependence of coercivity is explained by a size dependent demagnetizing factor. In Dy free Nd${}_2$Fe${}_{14}$B magnets the size dependent demagnetizing factor ranges from 0.2 for a grain size of 55 nm to 1.22 for a grain size of 8300 nm. The comparison of experimental data with micromagnetic simulations suggests that the grain size dependence of the coercive field in hard magnets is due to the non-uniform magnetostatic field in polyhedral grains.

References in corpus (2)

• LaBonte's method revisited: An effective steepest descent method for micromagnetic energy minimization
• Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets

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• Magnetism in Metastable and Annealed Compositionally Complex Alloys
• Inferring Grain Size Distributions from Magnetic Hysteresis in M-type Hexaferrites
• Role of twin and anti-phase defects in MnAl permanent magnets