First-order field-induced magnetization transitions in single-crystal Nd2Fe14B

Magnetization measurements in high-pulsed magnetic fields have revealed the presence of magnetic anisotropy in the hard basal plane of a single crystal of Nd2Fe14B. A discontinuity in the magnetization occurs when the magnetic field is applied along the [100] direction in the hard basal plane below 220 K while there is a regular approach to saturation magnetization along the [110] direction. This discontinuity has been interpreted as a first-order magnetization process. High-order terms in the free energy are required to account for the spin reorientation transition from easy axis to easy cone and first-order magnetization process. The temperature dependence of the uniaxial and planar anisotropy energy constants has been determined.