Pressure-enhanced magnetocaloric effects in Mn2Sb1-xSnx system with uniaxial magnetocrystalline anisotropy

Highlights: • Higher Sn substitution reducing magnetic entropy changes and T_c, but increasing the AFM-FIM transition temperature (T_t). • Hydrostatic pressure lowering T_t, suppressing spin reorientation and enhancing the magnetic entropy changes. • Uniaxial magnetocrystalline anisotropy unexpectedly discovered and abnormally increased with elevating temperature. • Microstructure changed greatly with increased Sn composition in Mn₂Sb_1-xSn_x ribbons. The magnetocaloric effects in Sn-substituted Mn₂Sb_1-xSn_x system (x = 0.1, 0.2, 0.3) have been studied. With more Sn content, metamagnetic phase transition temperature (T_t) is increased with gradually reduced Curie temperature, thermal hysteresis and the maximum of magnetic entropy change (ΔS^max). By hydrostatic pressure of 2.5 kbar, T_t is lowered but ΔS^max is enhanced from 4.2 JKg⁻¹K⁻¹ to ∼5.5 Jkg⁻¹K⁻¹ in Mn₂Sb_1-xSn_x (x = 0.1, 0.2) ingots. The uniaxial magnetocrystalline anisotropy is found in all Mn₂Sb_1-xSn_x ingots and abnormally increased with elevated temperature, leading to the abnormal coercivity-temperature dependence in the corresponding ribbons. The microstructure of the ribbons is sensitively dependent on Sn composition. Our work demonstrates that high ΔS^max tuned by hydrostatic pressure and high magnetocrystalline anisotropy can be realized together in Mn₂Sb_1-xSn_x system, which may help the development of such bifunctional alloy exhibiting refrigerating capability as well as the hard magnetic properties simultaneously.