Giant low-field magnetocaloric effect of (Er,Y)Cr2Si2 compounds at ultra-low temperatures

Low-temperature and low-field magnetocaloric materials with high magnetocaloric effect (MCE) performance have important prospects in applications such as gas liquefaction. A series of polycrystalline Er1−xYxCr2Si2 (0 ≤ x ≤ 0.8) samples were successfully synthesized by arc melting, showing giant low-field MCE. For the sample with x = 0.1, the compound shows the best MCE performance, with the appropriate working temperature down to 2 K. Furthermore, the maximum value of magnetic entropy change ((−ΔSM)max) and adiabatic temperature change ((ΔTad)max) under the field change of 0–1 T are calculated to be 19.2 J kg−1 K−1 and 4.3 K correspondingly. The value of (−ΔSM)max is the largest ever reported for intermetallic MCE materials below 20 K. The characteristic of magnetic phase transition is verified to be of second order on basis of Arrott plots, mean field theory and rescaled universal −ΔSM curves. The physical mechanism indicates that the great enhancement of (−ΔSM)max as large as 15.9% due to 10% Y substitution originates from the larger saturation magnetic moments and the smaller saturated magnetic fields.