Giant and highly anisotropic magnetocaloric effects in single crystals of disordered-perovskite RCr_0.5Fe_0.5O₃ (R = Gd, Er)

Magnetic anisotropy is crucial in examining suitable materials for magnetic functionalities because it affects their magnetic characteristics. In this study, disordered-perovskite RCr_0.5Fe_0.5O₃ (R = Gd, Er) single crystals were synthesized and the influence of magnetic anisotropy and additional ordering of rare-earth moments on cryogenic magnetocaloric properties was investigated. Both GdCr_0.5Fe_0.5O₃ (GCFO) and ErCr_0.5Fe_0.5O₃ (ECFO) crystallize in an orthorhombic Pbnm structure with randomly distributed Cr³⁺ and Fe³⁺ ions. In GCFO, the long-range order of Gd³⁺ moments emerges at a temperature of T _Gd (the ordering temperature of Gd³⁺ moments) = 12 K. The relatively isotropic nature of large Gd³⁺ moment originating from zero orbital angular momentum exhibits giant and virtually isotropic magnetocaloric effect (MCE), with a maximum magnetic entropy change of Δ S_M ≈ 50.0 J/kg·K. In ECFO, the highly anisotropic magnetizations result in a large rotating MCE characterized by a rotating magnetic entropy change Δ S_θ = 20.8 J/kg·K. These results indicate that a detailed understanding of magnetically anisotropic characteristics is the key for exploring improved functional properties in disordered perovskite oxides.