Magnetocaloric effect with low magnetic hysteresis loss in ferromagnetic Ni-Mn-Sb-Si alloys

Giant magnetocaloric effect in Ni-Mn-X (X=In, Sn, Sb) Heusler alloys has been revealed due to the significant shift of the martensite transformation temperatures under a bias magnetic field. However, the magnetic hysteresis during the magnetization and demagnetization cycles creates a large hysteresis loss and reduces the refrigeration capacity. Here we demonstrated that the magnetic hysteresis loss in Ni-Mn-Sb alloys was effectively reduced by Si-doping. The quaternary Ni_49.0Mn_38.4Sb_11.7Si_0.9 alloy exhibited martensite and magnetic transitions around room temperature. Maximum magnetic entropy change ΔS_m 9.4 J/kg K and working temperature interval 7.0 K were achieved attributed to the martensite transformation under a magnetic field of 5 T. Meanwhile, the average magnetic hysteresis loss for Ni_49.0Mn_38.4Sb_11.7Si_0.9 alloy was 2.1 J/kg, much smaller than that for Ni_49.0Mn_38.5Sb_12.5 alloy, 11.4 J/kg. As a result, a refrigeration capacity of 50.2 J/kg was obtained in the Ni_49.0Mn_38.4Sb_11.7Si_0.9 alloy. This result shows that Si-doped Ni-Mn-Sb alloys may act as a potential material system for magnetic refrigeration.