Magnetic entropy change and large refrigerant capacity of Ce₆i₂Si₃-type GdCoSiGe compound

Magnetic entropy change (\Delta S_\rm M) and refrigerant capacity (RC) of Ce_6Ni_2Si_3-type Gd_6Co_1.67Si_2.5Ge_0.5 compounds have been investigated. The Gd_6Co_1.67Si_2.5Ge_0.5 undergoes a reversible second-order phase transition at the Curie temperature T_\rm C = 296 K. The high saturation magnetization leads to a large \Delta S_\rm M and the maximal value of \Delta S_\rm M is found to be 5.9 J/kg\cdotK around T_\rm C for a field change of 0--5 T. A broad distribution of the \Delta S_\rm M peak is observed and the full width at half maximum of the \Delta S_\rm M peak is about 101~K under a magnetic field of 5 T. The large RC is found around T_\rm C and its value is 424 J/kg.