Magnetic properties of a DyFe5Al7 single crystal

A single crystal of DyFe5Al7 (tetragonal ThMn12 structure) has been studied. DyFe5Al7 orders ferrimagnetically at T-C = 231 K and has a compensation of the Dy and Fe sublattices at T-comp = 93 K. Magnetization isotherms measured along the principal axes of the single crystal indicate that the magnetic moments lie in the basal plane of the tetragonal lattice. Strong magnetic anisotropy is observed not only between the basal plane and the [0 0 1] axis but also within the basal plane, with the [1 0 0] axis being the easy magnetization direction with the spontaneous magnetic moment 2.1(mu B). A very high coercivity with H-c values up to 3 T was found at 2 K. In the temperature range 75-100 K, the compound exhibits a field-induced magnetic transition along the easy [1 0 0] direction. Temperature dependence of the critical field H-cr of the transition is very strong, the value of H-cr evidently exceeds 14 T below 75 K. A model for the magnetization process of a two-sublattice ferrimagnet with a weak intersublattice exchange interaction has been developed to explain the magnetic transition. The model reproduces the temperature behavior of H-cr near the compensation point. (C) 2011 Elsevier B. V. All rights reserved.