Cryogenic magnetocaloric effect in a disordered double-perovskite Gd₂MnZnO₆

This work presents an investigation on the structural characterization, magnetic behavior, and cryogenic magnetocaloric (MC) effect of a disordered double-perovskite Gd₂MnZnO₆ prepared via a solid-state reaction method. Powder X-ray diffraction analysis reflects that the title compound crystallizes in an orthorhombic structure with the Pnma space group. Its MC performance has been systematically assessed by means of the magnetic entropy change (|ΔS _m|), adiabatic temperature change (ΔT _ad) and heat capacity C _p. As a result, under an applied field of 40 kOe, the directly measured ΔT _ad reaches approximately 2.6 K. Meanwhile, the largest |ΔS _m| and relative-cooling power values (RCP) are about 19 J kg^-1 K^-1 and 331 J kg^-1, respectively, for a magnetic-field change of 90 kOe. Such large values of the parameters characteristic for the MC effect make Gd₂MnZnO₆ a promising candidate for cryogenic magnetic refrigeration. Furthermore, analysis of the M(T, H) and |ΔS _m(T)| data around the magnetic-phase transition indicates the presence of short-range magnetic order. This behavior is attributed to the coexistence of competing ferromagnetic and antiferromagnetic interactions in Gd₂MnZnO₆.