Structure, magnetism and magnetocaloric effect in a new triangular lattice compound Gd₃Cu₉(OH)₁₉Br₈

A new triangular lattice compound Gd₃Cu₉(OH)₁₉Br₈ has been synthesized by the hydrothermal method. The structure, magnetism and magnetocaloric effect of Gd₃Cu₉(OH)₁₉Br₈ have been studied by X-ray diffraction, magnetic susceptibility, isothermal magnetization and specific heat measurements. In Gd₃Cu₉(OH)₁₉Br₈, the Cu²⁺ ions form a Kagome lattice along the ab plane, and Gd³⁺ ions are located in the center of hexagonal holes of the Kagome layer. The Cu-sublattice and Gd-sublattice overlap and constitute a magnetic triangular lattice. The temperature dependence of susceptibility and specific heat curves indicate no magnetic transition down to 2 K, suggesting a paramagnetic-like behavior at low temperature. The magnetocaloric effect (MCE) at low temperature has been calculated according to Maxwell's equations. The maximum value of magnetic entropy change -ΔS _M is 26.04 J kg^-1 K^-1 and adiabatic temperature change ΔT _ad is 13.79 K, for a field change of 0-7 T, indicating a potential application of this compound in the field of magnetic refrigeration at low temperature. The influence of 4f-3d interaction on magnetism and MCE is also discussed.