Large low-field magnetocaloric performances of the ErCu_1.95T_0.05Si₂ (T = Mn, Fe, Co and Ni) compounds

Magnetocaloric materials are at the heart of magnetic refrigeration (MR) technology. However, there is a scarcity of materials with a large magnetocaloric effect (MCE) at magnetic fields below 2 T. To address this limitation, we investigate the effect of doping in the ErCu₂Si₂ compound with relatively inexpensive neighboring atoms of Mn, Fe, Co, and Ni in the Cu position, respectively. The results show a significant enhancement in the MCE at low fields. Under the magnetic field change of 0–2 T, the values of maximum magnetic entropy change (−ΔS_M^max) for the ErCu_1.95T_0.05Si₂ (T = Mn, Fe, Co and Ni) compounds are 16.4 J/kg·K, 17.5 J/kg·K, 17.8 J/kg·K, and 18.6 J/kg·K, respectively. Compared to those of the parent compound ErCu₂Si₂, the −ΔS_M^max of the ErCu_1.95T_0.05Si₂ (T = Mn, Fe, Co and Ni) compounds exhibit enhancements of 3%, 11%, 13%, and 17%, respectively. Additionally, the magnetic transition temperatures of these doped compounds are lower than that of the parent compound ErCu₂Si₂, occurring below 2 K. Therefore, ErCu_1.95T_0.05Si₂ (T = Mn, Fe, Co and Ni) compounds with large low-field MCE and negligible loss of hysteresis have the potential to serve as candidate materials for cryogenic magnetic refrigeration.