Magnetic anisotropy of MnAl and MnAlC permanent magnet materials

The magnetocrystalline anisotropy of MnAl and MnAlC alloys, in the range of existence of the ferromagnetic τ phase, has been studied by using the singular point detection technique. The anisotropy field value at 293 K varies from 39 kOe for low manganese and high carbon content to 55 kOe for high manganese and carbon-free samples. The anisotropy of the MnAl τ phase is well described by using only the K1 anisotropy constant. The temperature dependence of the calculated anisotropy constant indicates that a single ion mechanism is the origin of the magnetocrystalline anisotropy in these alloys.