Giant low-field reversible magnetocaloric effect in HoCoGe compound

Abstract

Magnetic properties and magnetocaloric effects (MCEs) of the HoCoGe compound have been investigated by magnetization and heat capacity measurements. The HoCoGe compound undergoes a second-order ferromagnetic–paramagnetic phase transition around the Curie temperature T_C = 7.6 K and exhibits a giant reversible MCE. For a field change of 0–5 T, the maximum values of magnetic entropy change (−ΔS_M) and adiabatic temperature change (ΔT_ad) are 23.9 J kg⁻¹ K⁻¹ and 10.9 K, respectively. A large refrigerant capacity of 402 J kg⁻¹ is also observed. In particular, the maximum values of −ΔS_M and ΔT_ad are high, at 17.1 J kg⁻¹ K⁻¹ and 6.0 K respectively, for a field change of 0–2 T. These results show that the HoCoGe compound with excellent magnetocaloric effects can be expected to have effective applications in low temperature magnetic refrigeration.