High-field magnetization of a DyFe₅Al₇ single crystal

The magnetization of a DyFe₅Al₇ single crystal with the tetragonal ThMn₁₂-type structure was measured in pulsed fields up to 60 T along the principal axes. The compound orders ferrimagnetically at T_C = 231 K and exhibits a compensation of the Dy and Fe sublattices at T_comp = 93 K. DyFe₅Al₇ displays a high magnetic anisotropy of the easy-plane type, the [100] axis is the easy magnetization direction with the spontaneous magnetic moment M_s = 2.1 µ_B/f.u. at T = 2 K. In a field applied along the easy axis, two field-induced hysteretic transitions are observed at 30 and 53 T at T = 2 K. The critical field H of the first transition depends strongly on temperature, whereas H_cr2 is practically temperature-independent. Above the transitions the magnetization continues to grow as a function of field, as the sublattice moments continue to rotate. To reach the full saturation (forced ferromagnetic state), fields of several Tesla higher than 60 T are required. The field dependence of magnetization along the easy [100] axis was analyzed within a model for a ferrimagnet with an anisotropic dominant sublattice. The model correctly reproduces the behavior of magnetization in a magnetic field. The intersublattice molecular field on Dy and the basal-plane anisotropy constant of the Dy sublattice have been determined.