Cryogenic magnetocaloric effect of rare-earth halide perovskites CsEuCl3 and CsEuBr3

Abstract

Adiabatic demagnetization refrigeration (ADR) offers a compelling alternative to traditional ultra-low temperature technologies by eliminating the reliance on scarce 3He and gravitational constraints. The key of ADR development is to find magnetic refrigerants with exceptional magnetocaloric properties. In this study, polycrystalline CsEuCl3 and CsEuBr3 halide perovskites were synthesized by a simple solid-phase reaction method. CsEuCl3 crystallizes in a tetragonal structure, while CsEuBr3 forms an orthorhombic structure, both exhibiting distorted perovskite structures. CsEuCl3 undergoes an antiferromagnetic ordering at TN ∼ 1.1 K, whereas CsEuBr3 shows no magnetic ordering above 0.4 K. Curie–Weiss fitting analysis reveals antiferromagnetic interactions in both compounds, with CsEuBr3 displaying stronger antiferromagnetic coupling. The maximum magnetic entropy change (−ΔSM) values under magnetic field changes of 0–2 T and 0–5 T are 22.4 and 38.6 J kg−1 K−1 at 1.4 K for CsEuCl3, and 15.7 and 26.4 J kg−1 K−1 at 0.4 K for CsEuBr3, respectively. These findings underscore the potential of CsEuCl3 and CsEuBr3 as promising candidates for cryogenic magnetic refrigeration applications.