Abstract
Magnetization and ultrasound measurements have been performed in pulsed magnetic fields up to 60 T on a ferrimagnetic HoFe5Al7 single crystal (Curie temperature T-C = 216 K, compensation point T-comp = 65 K) with a tetragonal crystal structure of the ThMn12- type. The compound exhibits a high magnetic anisotropy of the easy-plane type.
A large anisotropy is also observed within the basal plane having an easy-magnetization direction along the [110] axis with the spontaneous magnetic moment M-s = 2 mu(B)/f.u. at T = 2 K. Along the easy axis, two first-order field-induced magnetic transitions are observed.
At both transitions sharp anomalies in the acoustic properties are found. The critical fields of the transitions depend on temperature in a different manner.
Within molecular-field theory and using the high-field magnetization data the Ho-Feinter-sublattice exchange parameter has been determined to be n(HoFe) approximate to 4 T/mu(B). The magnetoelasticity has also been probed by magnetization measurements under hydrostatic pressure.
TC decreases with a rate dT(C)/dp = -10 K/GPa, whereas Tcomp increases with dT(comp)/dp = 3.5 K/GPa.