Determination of the magnetocaloric effect associated with martensitic transition in Ni₄₆Cu₄Mn₃₈Sn₁₂ and Ni₅₀CoMn₃₄In₁₅ Heusler alloys

This paper presents a study of the inverse magnetocaloric effect (MCE) corresponding to martensitic transition using various experimental approaches for Ni₄₆Cu₄Mn₃₈Sn₁₂ and Ni₅₀CoMn₃₄In₁₅ Heusler alloy. Through heat capacity measurements, it is found that the "giant inverse MCE" upon martensitic transition evaluated by the Maxwell relation in these alloys are unphysical results. This is due to the coexistence of both martensitic and austenitic phases, as well as thermal hysteresis during martensitic transition. However, careful study indicates that the spurious results during martensitic transition can be removed using a Clausius-Clapeyron equation based on magnetization measurements.