Magnetic properties of a DyFe5Al7 single crystal

A single crystal of DyFe5Al7 (tetragonal ThMn12 structure) has been studied. DyFe5Al7 orders ferrimagnetically at TC = 231 K and has a compensation of the Dy and Fe sublattices at Tcomp = 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 2.1μB. A very high coercivity with Hc 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 Hcr of the transition is very strong, the value of Hcr 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 Hcr near the compensation point.

► RFe5Al7 (R – rare-earth metal) compounds are complicated magnetic systems.
► There are competitive exchange and isotropic interactions between the R and Fe sublattices in RFe5Al7.
► A single crystal of DyFe5Al7 is grown for the first time and its magnetic properties are systematically studied.