Direct observations of first-order magnetization processes in single-crystalNd2Fe14B

Discontinuities in the magnetization curve of a uniaxial single crystal of ${\mathrm{Nd}}_2$ ${\mathrm{Fe}}_{14}$B along the hard direction are reported. The discontinuities, which have been interpreted as first-order magnetization process (FOMP’s), have been observed below 200 K in high magnetic fields. The critical field at which the FOMP occurs increases with decreasing temperature. The results are discussed in terms of the phenomenological anisotropy-energy description of uniaxial ferromagnets.