Reduction of magnetic hysteresis loss in La_0.5Pr _0.5Fe_11.4Si_1.6H_x hydrides with large magnetocaloric effects

Magnetic properties and magnetocaloric effects (MCEs) have been investigated in hydrogenated La_0.5Pr_0.5Fe _11.4Si_1.6H_x (x=0, 0.9, and 1.6) compounds. It is found that the Curie temperature T_C can be tuned from 189 to 317 K by adjusting hydrogen content from 0 to 1.6. It is attractive that both thermal and magnetic hysteresis are remarkably reduced because of the weakness of the itinerant-electron metamagnetic transition after hydrogenation, while the large magnetic entropy change is retained. The maximal hysteresis loss at T _C decreases from 17.8 to 2.3 J/kg as x increases from 0 to 1.6. For the samples with x=0, 0.9, and 1.6, the maximal values of -ΔS are 26.3, 24.1, and 22.1 J/kg K at T_C, with efficient refrigeration capacities of 463, 366, and 351 J/kg for a field change of 0-5 T, respectively. Large reversible MCE and small hysteresis with considerable value of refrigeration capacity indicate the potentiality of La_0.5Pr_0.5Fe _11.4Si_1.6H_x hydrides as a candidate magnetic refrigerant around room temperature.