Cryogenic magnetocaloric effect of the CaErAlO4 compound

The magnetism and magnetocaloric effect (MCE) of some rare-earth (RE)-based oxides have attracted special attention due to their interesting physical and chemical properties, such as easy fabrication and high chemical stability. In this paper, the CaErAlO4 polycrystal compound synthesized by the high-temperature solid-state method manifests the considerable second-order reversible MCE near the temperature of liquid helium. This compound crystallizes in the perovskite-like K2NiF4-type structure with the space group of I4/mmm. The negative paramagnetic Curie temperature suggests that antiferromagnetism is dominant in the material and the moderate magnetization is mainly contributed by the ferromagnetic interaction in the sample. The measured isothermal magnetic entropy changes (-Delta SM) at 3 K are 14.3 and 22.9 J/kg K under 0-20 and 0-50 kOe field changes, respectively. They are greater than those of most RE-based oxides. Our results indicate that the CaErAlO4 compound is a promising candidate for cryogenic magnetic refrigeration.