Large reversible magnetocaloric effect in RMn2 (R=Tb, Dy, Ho, Er) compounds

•A positive value of ΔSM for TbMn2 is 8.3Jkg−1K−1 under the field change of 0.1T.•The maximum ΔSM for ErMn2 is 13.4Jkg−1K−1 under the field changes of 0.2T.•The maximum ΔSM for ErMn2 is 25.5Jkg−1K−1 under the field changes of 0.5T.•The RC for HoMn2 is 404.3Jkg−1 under the field changes of 0.5T.•The larger ΔSM and RC are not thermal and magnetic hysteresis loss. Magnetocaloric effect (MCE) of RMn2 (R=Tb, Dy, Ho, Er) compounds are investigated. TbMn2 and DyMn2 crystallize in cubic Laves phase structure (C15 type), whereas HoMn2 and ErMn2 crystallize in hexagonal Laves phase structure (C14 type). For TbMn2 compound, the field-induced metamagnetic transition accompanying a spontaneous cell volume expansion is observed (inverse MCE), which leads to a large positive value (8.3Jkg−1K−1) of magnetic entropy change around 36K under the field change of 0–1T, while the maximal values of magnetic entropy change (ΔSM) and the refrigerant capacity (RC) for other RMn2 (R=Dy, Ho, Er) compounds are −15.7, −18.4, −25.5Jkg−1K−1 and 403.6, 404.3, 316.0Jkg−1 around their TC with negligible thermal and magnetic hysteresis loss for the field change of 0–5T, respectively. The results suggest that RMn2 (R=Dy, Ho, Er) may be appropriate candidates for magnetic refrigerant working at low temperature region 10–80K.