Giant Magnetic Entropy Change in Hydrogenated La(Fe0.88Si0.12)13Hy Compounds

A magnetic entropy change ∆S M due to the itinerant-electron metamagnetic (IEM) transition was estimated to be -23 J/kg K around the Curie temperature for La(Fe 0.88 Si 0.12 ) 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 ∆S M , hydrogen absorption was carried out.La(Fe 0.88 Si 0.12 ) 13 H 1.0 with T C = 274 K shows a large ∆S M due to the IEM transition around room temperature.The adiabatic temperature change ∆T ad from 0 to 2 T is about 7 K, comparable to that of Gd 5 (Ge 0.5 Si 0.5 ) 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 ∆S M is almost the same after hydrogen absorption.Therefore, the hydrogenated La(Fe 0.88 Si 0.12 ) 13 H y compounds are promising magnetic refrigerants working in a wide range of temperature.