Determining anisotropy constants from a first-order magnetization process in Tb2Fe17

The critical parameters of a first-order magnetization process, Hcr and mcr, are used to determine the anisotropy constants K1 and K2 of Tb2Fe17 in the temperature range between 5 and 300 K. Both anisotropy constants are proportional to the critical field Hcr (times spontaneous magnetization), whereas their ratio is independent of Hcr and depends solely on the dimensionless reduced critical magnetization mcr. The employed method of determining K1 and K2 is complementary to the classical Sucksmith–Thompson technique, which is inapplicable in the case of a first-order magnetization process.