A Brilliant Magnetic Refrigerant Operating Near Liquid Helium Temperature: Enhanced Magnetocaloric Effect in Ferromagnetic EuTi_0.75Al_0.125Zr_0.125O₃

Rare earth-based perovskites have become an attractive research interest in the field of cryogenic magnetic refrigerants due to their unique advantages in practical applications. The remarkable magnetocaloric effect (MCE) renders EuTiO₃ a potential magnetic refrigerant in the liquid helium temperature range. More impressively, the tunability between antiferromagnetism (AFM) and ferromagnetism (FM) provides the feasibility of tailoring the magnetism and enhancing the magnetocaloric performance. In this study, the magnetism of EuTi_0.75Al_0.125Zr_0.125O₃ is investigated in depth through first-principles calculations and experimental methods. Both theoretical calculations and experimental results reveal that it exhibits significant ferromagnetism due to the AFM-FM magnetic transition promoted by the co-substitution of Al and Zr. Lattice expansion and altered electronic interactions are responsible for the FM behavior, which leads to a significant enhancement of the MCE. With the field change of 0−1 T, the peak values of magnetic entropy change (−ΔS_M), refrigerating capacity (RC), and adiabatic temperature change (ΔT_ad) reach 18.9 J kg⁻¹ K⁻¹, 77.7 J kg⁻¹, and 7.4 K, respectively. More surprisingly, the values of maximum magnetic entropy change ((Formula presented.)) and maximum adiabatic temperature change (Formula presented.) for EuTi_0.75Al_0.125Zr_0.125O₃ reach 11.4 J kg⁻¹ K⁻¹ and 3.7 K under the field change of 0−0.5 T, respectively. The remarkable magnetocaloric performance proves it to be a brilliant magnetic refrigerant operating near liquid helium temperature.