Investigation of the effect of martensitic phase transition temperature and Curie temperature difference on magnetic and magnetocaloric properties under low magnetic field on Si-doped Ni-Mn-In Heusler Alloys

This study examines the impact of substituting Si for Mn on the structural, magnetic, and magnetocaloric properties of Ni 43 Mn 46− x Si x In 11 (x = 0.3 and 0.6) alloys. To this end, a range of analytical techniques are employed, including scanning electron microscopy (SEM), room temperature x-ray powder diffraction (XRD), and magnetization measurements. Above the martensitic transition temperature, the Ni 43 Mn 46− x Si x In 11 alloys exhibit cubic L2 1 (space group FM-3M). Below this temperature they adopt a tetragonal L1 0 (space group I4/mmm). The martensitic transition temperature decreased when Si is substituted for Mn. The magnetic field-induced entropy change is calculated from magnetic field-dependent magnetization measurements using Maxwell’s equations. The maximum magnetic field-induced entropy changes for Ni 43.16 Mn 45.56 Si 0.29 In 11 and Ni 43.51 Mn 44.82 Si 0.59 In 11 alloys are calculated 8.20 J kg −1 K −1 and 3.15 J kg −1 K −1 , respectively, in the vicinity of the magnetostructural phase transition for a magnetic field change of 18 kOe. It is demonstrated that the temperature differential between the high-temperature austenite phase's Curie point ( T C ) and the mean martensitic transformation temperature ( T M ), namely ( T M - T C ), influences the martensitic transition temperatures and, consequently, on the magnetic field-induced entropy change (Δ S M ).