Control of large magnetocaloric effects in metamagnetic La(Fe _xSi_1-x)₁₃ compounds by hydrogenation

To obtain large magnetocaloric effects (MCEs) due to the itinerant-electron metamagnetic (IEM) transition in La(FexSi1-x)13, the Curie temperature TC has been controlled by hydrogen absorption. In La(Fe0.88Si0.12)13Hy compounds, TC=195 K for y=0.0 increases with increasing hydrogen concentration, resulting in TC=330 K for y=1.6. Furthermore, the magnetic moment is also stabilized against temperature by hydrogen absorption. Since the IEM transition is preserved after hydrogenation, large MCEs of the magnetic entropy change ΔSm and the adiabatic temperature change ΔTad have been observed around room temperature. A large value of ΔTad has been confirmed by a direct measurement in adiabatic magnetic field change for the La(Fe0.89Si0.11)13Hy (y=0.0 and 1.6). Consequently, the La(FexSi1-x)13 compounds and their hydrides are promising as high-performance magnetic refrigerants working in a wide range of temperature covering room temperature in relatively low applying magnetic fields.