Giant magnetic entropy change in hydrogenated La(Fe0.88Si0.12)13Hy compounds

Abstract

A magnetic entropy change ΔSM due to the itinerant-electron metamagnetic (IEM) transition was estimated to be -23 J/kg K around the Curie temperature for La(Fe0.88Si0.12)13 in the magnetic field change from 0 to 5 T. In order to control the Curie temperature while keeping such a large value of ΔSM, hydrogen absorption was carried out. La(Fe0.88Si0.12)13H1.0 with TC = 274 K shows a large ΔSM due to the IEM transition around room temperature. The adiabatic temperature change ΔTad from 0 to 2 T is about 7 K, comparable to that of Gd5(Ge0.5Si0.5)4. By changing the hydrogen concentration, the Curie temperature can be controlled from 195 to 336 K. It should be noted that the magnitude of ΔSM is almost the same after hydrogen absorption. Therefore, the hydrogenated La(Fe0.88Si0.12)13Hy compounds are promising magnetic refrigerants working in a wide range of temperature.