Demagnetization curves at different temperatures for single-phase nanocrystalline Nd-Fe-B magnets studied micromagnetically

The demagnetization curves at different temperatures between 4 and 250 K were calculated for single-phase nanocrystalline Nd-Fe-B magnets by using the micromagnetic finite-element technique. The calculations were carried out for a model magnet comprised of 216 grains of dimension 20 nm, taking into, account the anisotropic characteristics of the curve with respect to the field direction. The calculations simulate the experimental curves for the nanocrystalline Nd₁₃Fe₇₇B₁₀ magnet fairly well. The inter-grain exchange interaction in the magnet is estimated to be about 75% of the intra-grain exchange interaction.