Large magnetic entropy change and magnetic properties in La(Fe_1-xMn_x)_11.7Si_1.3H_y compounds

Magnetic properties and magnetic entropy change in La(Fe_1-xMn_x)_11.7Si_1.3H_y compounds have been investigated. A significant increase of the Curie temperature T_\rm C and a small increase of the saturation magnetizations \mu_\rm S have been observed after the introduction of interstitial H, which caused a slight volume expansion. The first-order field-induced itinerant-electron metamagnetic (IEM) transition remains and brings about a large magnetic entropy change around room temperatures for the compounds. The maximal magnetic entropy change is about 23.4, 17.7 and 15.9J/kg·K under a magnetic field change from 0 to 5T for x=0.01, 0.02 and 0.03, respectively. Therefore, the compounds appear to be potential candidates for magnetic refrigerants around room temperatures.