Low-field large reversible magnetocaloric effect in the RNi2Si2 (R=Dy, Ho, Er) compounds

The magnetocaloric effect (MCE) of RNi2Si2 (R=Dy, Ho, Er) compounds with the ThCr2Si2-type body-centered tetragonal structure are investigated. RNi2Si2 compounds are antiferromagnetic (AFM) with Néel temperature TN=6.5 K, 4.9 K, and 3.5 K, respectively. A field-induced metamagnetic transition from AFM-to-ferromagnetic (FM) state is found below TN, which leads to a large MCE around the TN. The maximal values of magnetic entropy change (ΔSM) for RNi2Si2 (R=Dy, Ho, Er) reach −6.9, −10.9, and −15.1 Jkg−1 K−1 and −21.3, −21.7, and −21.3 Jkg−1 K−1 without thermal and magnetic hysteresis losses for the field changes of 0-2 T and 0-5 T, respectively. The large ΔSM is associated with the field-induced first-order AFM-FM metamagnetic transition and low critical field. The excellent MCE under low field change without hysteresis loss suggests that RNi2Si2 (R=Dy, Ho, Er) can be an appropriate candidate for magnetic refrigerant in liquid helium temperature ranges.