Large reversible magnetocaloric effect in antiferromagnetic HoNiSi compound

Magnetic properties and magnetocaloric effect (MCE) of intermetallic HoNiSi compound have been investigated systematically. It is found that HoNiSi exhibits antiferromagnetic (AFM) state below the Néel temperature TN of 3.8 K, which is quite close to the liquid helium temperature (4 K). A giant MCE without hysteresis loss is observed in HoNiSi, which is related to the field-induced first-order metamagnetic transition from AFM to ferromagnetic states. For a magnetic field change of 2 T, the maximum values of magnetic entropy change (−ΔSM) and adiabatic temperature change (ΔTad) are 17.5 J/kg K and 4.5 K, respectively. In addition, HoNiSi presents both large values of positive and negative ΔSM for the low field changes, i.e., the maximum −ΔSM values are 9.2 J/kg K around TN and −7.2 J/kg K below TN for the field changes of 1 and 0.5 T, respectively. A universal curve of ΔSM is successfully constructed by using phenomenological procedure, proving the applicability of universal ΔSM curve for AFM materials. The giant reversible MCE for relatively low magnetic field change makes HoNiSi attractive candidate for magnetic refrigerant materials around liquid helium temperature.