Magnetocaloric effect of the ternary Dy, Ho and Er platinum gallides

Abstract

Magnetic and magnetocaloric properties of equiatomic ternary gallides RPtGa (R=Dy, Ho and Er) compounds have been reported. All these compounds are iso-structural and order antiferromagnetically below 20K. External applied magnetic field induces metamagnetic transition from antiferromagnetic to ferromagnetic state. Adiabatic entropy change (−ΔSM) shows negative contribution for magnetic field changes up to 10kOe (for R=Ho and Er) and 30kOe (for R=Dy) due to disordering of antiparallel spins with the external applied field. As the field change increases, only a positive asymmetric peak is observed. A broad −ΔSM peak is observed for HoPtGa, evidencing characteristics of a table-like behavior. HoPtGa and ErPtGa present the largest magnetocaloric effect (EMC) compared with DyPtGa, indicating that the nature of metamagnetic transition affects the magnetocaloric properties. The maximum value of adiabatic temperature change ( ∆Tadmax) obtained for R=Dy, Ho and Er was respectively 4.1K, 4.9K and 6.7K for ΔH=50kOe. These values are comparable with the respective ∆Tadmax reported for other RTX compounds in the same range of temperature and suggest that RPtGa compounds are attractive candidates for magnetic refrigeration in low temperature range (<20K) with the advantage of not presenting hysteresis loss.