Large magnetocaloric effect in triangular antiferromagnet ErPd₂Sb

Adiabatic demagnetization refrigeration (ADR) has been considered as an main method for achieving temperature below 1 K. Due to the absence of long-range magnetic ordering at extremely low temperature, frustrated magnets are very competitive in cryogenic magnetic refrigerants. In this paper, we investigated the magnetocaloric effect of triangular antiferromagnet ErPd₂Sb. No evident manetic ordering can be observed at temperature above 0.56 K. Large volumetric magnetic entropy change of 172.8 mJ·cm⁻³·K⁻¹ is obtained under a small field change of 2 T at 1.3 K, which is larger than that of commercial magnetic refrigerant Gd₃Ga₅O₁₂ under the same condition. Due to the strong magnetic frustration, the minmum temperature of ErPd₂Sb is revealed to be 254.8 mK by quasi-ADR measurement, which is much lower than its magnetic ordering temperature. In addition, a field-induced phase trantition can be marked in ADR curve at 0.5 T, which is consistent with the measurement results of electrical resistivity. These excellent magnetocaloric effects indicate that ErPd₂Sb is an ideal candidate for ultra-low temperature magnetic refrigeration application.