Magnetocaloric effect and magnetic transition in bulk Mn1.1Fe0.9P0.8Ge0.2 compound

Crystal structure, magnetocaloric effect and magnetic transition in bulk Mn1.1Fe0.9P0.8Ge0.2 compound have been studied by X-ray diffraction, magnetic measurements and Landau–Ginzberg theory. Mn1.1Fe0.9P0.8Ge0.2 compound crystallizes in a hexagonal Fe2P-type structure with lattice constants of a = 6.0789(10) Å and c = 3.4674(9) Å. The compound exhibits giant magnetocaloric effect with maximum magnetic entropy change of 61.8 J/kg K in a field change from 0 to 5 T around its Curie temperature of 251 K. The temperature dependence of the Landau coefficients have been derived by fitting the magnetization with the Landau expansion of the magnetic free energy, indicating the first-order nature of the magnetic transition between ferromagnetic and paramagnetic states in the compound.