Magnetic properties and magnetocaloric effect in Tm-based magnesium compounds Tm4PdMg and Tm4PtMg

The magnetic and the magnetocaloric properties of Tm4PdMg and Tm4PtMg have been investigated. A second order magnetic phase transition from a paramagnetic to a ferromagnetic state was observed for Tm4PdMg and Tm4PtMg at the Curie temperatures of TC ∼6.0 and 4.5 K, respectively. A large reversible magnetocaloric effect was observed for both compounds at low temperature. For a magnetic field change of 7 T, the values of maximum magnetic entropy change (-ΔSMmax), refrigerant capacity (RC) and relative cooling power (RCP) are 18.0 J/kg K, 319 J/kg and 414 J/kg for Tm4PdMg, and 16.5 J/kg K, 275 J/kg and 353 J/kg for Tm4PtMg, respectively.