Tuning magnetostructural transition and the associated giant magnetocaloric effect via thermal treatment in MnCoGe-based alloys

The changes in magnetostructural transition behaviors and magnetocaloric effect with different stress states were studied by controlling the annealing and cooling processes for Mn_1−xCo_1+xGe alloys. Water quenching inhibits the structural transition in the investigated composition and temperature ranges, while furnace cooling results in coupled magnetostructural transitions. An additional annealing at an intermediate temperature followed by program-controlled slow cooling results in sharper transition, higher transition temperature, lower thermal hysteresis, higher field-sensitivity, and higher entropy change. Giant magnetocaloric effects were observed at different temperature regions for the samples subjected to different thermal treatments.