Magnetic properties and magnetocaloric effects in Gd _1-xHo _xNiIn intermetallic compounds

Magnetic properties and magnetocaloric effects (MCEs) of the intermetallic Gd _1-xHo _xNiIn (x=0-1) compounds have been evaluated by magnetization and heat capacity measurements. The Curie temperature T _C can be tuned from near 100 K to 20 K by substituting Ho for Gd atoms. In addition, all the compounds with Ho atoms undergo two successive magnetic transitions with the decrease of temperature: a paramagnetic (PM) to ferromagnetic (FM) transition around T _C and a spin-reorientation (SR) transition around 7-9 K. It is found that both transitions contribute to the magnetic entropy change (ΔS _M). For a field change of 5 T, the maximum values of -ΔS _M for Gd _0.4Ho _0.6NiIn are 6 J/kg K at T _t=9 K and 10 J/kg K at T _C=52 K, respectively. These two -ΔS _M peaks overlap partly and result in a wide working temperature range of MCE, and thus leading to the largest RC value of 443 J/kg in the Gd _1-xHo _xNiIn system.