Effects of Co and Si co-doping on magnetostructural transformation and magnetocaloric effect in Ni-Mn-Sn based alloys

Abstract The remarkable magnetocaloric effect demonstrated in Ni-Mn-based multi-functional alloys benefits a lot from large magnetization difference ΔM and low thermal hysteresis ΔHhys upon the magnetostructural transformation. Here, we present the effective manipulation of the magnetostructural transformation as well as the related magnetocaloric effect through simultaneously introducing Co and Si to ternary Ni-Mn-Sn alloys. Such co-doping method allows not only large magnetization difference but also low thermal hysteresis, yielding giant inverse magnetocaloric effect in a Ni39Co9Mn42Sn9Si1 alloy. Under the magnetic field change of 5 T, the field-induced entropy change ΔSM up to 23.5 Jkg−1K−1 and the reversible ΔSM of 23.4 Jkg−1K−1 are obtained. Moreover, giant refrigeration capacity up to 402 Jkg−1 is also achieved, being much higher than those reported previously. Furthermore, large field-induced adiabatic temperature change ΔTad up to −4.0 K and reversible ΔTad of −1.8 K are demonstrated through the direct measurements under a low magnetic field change of 1.5 T. Thus, multi-component alloying could be employed as an effective route towards the design of high-performance Heusler-type magnetocaloric materials.