Magnetic properties and magnetocaloric effect in the rare earth-rich phases RE4PtMg (RE = Ho and Er)

• RE4PtMg (RE = Ho and Er) were synthesized by induction melting method.
• Magnetism and magnetocaloric effect in RE4PtMg (RE = Ho and Er) were studied.
• Large reversible magnetocaloric effect was observed for both compounds.
• RE4PtMg (RE = Ho and Er) are good candidates for magnetic refrigeration.

The magnetic and magnetocaloric properties of Ho4PtMg and Er4PtMg with cubic Gd4RhIn-type structure have been investigated by magnetization and heat capacity measurements. The compounds undergo a second order magnetic phase transition from a paramagnetic to a ferromagnetic state at Curie temperatures of TC ∼ 28 and 16 K for Ho4PtMg and Er4PdMg, respectively. A large reversible MCE was observed around TC for both compounds. For a field change of 0–7 T, the maximum values of magnetic entropy change (−ΔSMmax) are 16.9 and 22.5 J/kg K for Ho4PtMg and Er4PtMg, respectively. The corresponding maximum values of adiabatic temperature change (ΔTadmax) are 5.3 and 6.5 K.