Giant low-field magnetocaloric effect in Si alloyed Ni-Co-Mn-In alloys

Abstract

For NiMn-based Heusler alloys, simultaneously achieving high magnetization difference and low thermal hysteresis across the magnetostructural transformation is of crucial importance to obtain large low-field actuated magnetocaloric properties. Here, the fifth element Si was introduced to replace In for reducing the thermal hysteresis in Ni-Co-Mn-In alloys while keeping a large magnetization change through the martensitic transformation. Consequently, a giant maximum entropy change ΔSMmax of 33.6 J kg−1 K−1 under the low field change of 2 T was achieved in a Ni45Co5Mn37In12Si1 alloy, which is among the highest values reported in NiMn-based alloys.