Cryogenic magnetocaloric properties in Xenotime-type HoPO₄

Holmium orthophosphate (HoPO₄) was prepared using the solid-state method. The XRD pattern analyses have proved that HoPO₄ crystallises in the tetragonal structure (I4₁ \(/\) $/$ amd). The maximum magnetic entropy change (− \(\Delta {S}_{\text{M}}^{\text{max}})\) $\mathrm{\Delta }{S}_{\text{M}}^{\text{max}})$ and the relative cooling power (RCP) reach 34.5 J \(/\) $/$ kg·K and 414.84 J kg⁻¹ at 2.4 K under a magnetic field of 50 kOe, respectively. The lowest transition temperature and the large magnetocaloric effect (MCE) showed that HoPO₄ is a potential candidate for superfluid helium magnetic refrigeration applications.