High-field magnetization study of a HoFe6Al6 single crystal

• the HoFe6Al6 compound (tetragonal crystal structure) was studied on a single crystal.
• HoFe6Al6 has a compensation point at 4.2 K.
• HoFe6Al6 is a strongly anisotropic ferrimagnet, [110] is the easy magnetization axis.
• HoFe6Al6 displays field-induced phase transitions along the [100] and [110] axes.
• the transitions are explained based on the model for isostructural HoFe5Al7.

Magnetization measurements have been performed in static (up to 14 T) and pulsed (up to 60 T) magnetic fields on a HoFe6Al6 single crystal with a tetragonal crystal structure of ThMn12 type. HoFe6Al6 is a ferrimagnet with exact compensation of the Ho and Fe sublattices at low temperatures, the spontaneous magnetic moment is Ms = 0 at 4.2 K. At elevated temperatures, Ms passes through a wide maximum (4.2 μB at 200 K) and vanishes at the Curie temperature, TC = 315 K. The compound displays a high magnetic anisotropy of the easy-plane type, a noticeable anisotropy exists also within the easy plane with the [110] axis as the easy magnetization direction. HoFe6Al6 exhibits two field-induced magnetic phase transitions along the easy [110] axis and two more along the [100] axis, the hard direction in the basal plane. The critical fields of the lower- and higher-field transitions display qualitatively different temperature dependencies. A T–H magnetic phase diagram has been constructed for the [100] and [110] directions. The Ho–Fe inter-sublattice exchange constant has been determined to be nHoFe = 3.8 T/μB.

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