The effect of different atomic substitutions at Mn sites on the magnetic and magnetocaloric properties in Ni
50Mn
35Co
2Sn
13 alloy has been studied in detail. The substitution of Ni or Co for Mn atoms might lower the Mn
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The effect of different atomic substitutions at Mn sites on the magnetic and magnetocaloric properties in Ni
50Mn
35Co
2Sn
13 alloy has been studied in detail. The substitution of Ni or Co for Mn atoms might lower the Mn content at Sn sites, which would reduce the
d-d hybridization between Ni 3
d eg states and the 3
d states of excess Mn atoms at Sn sites, thus leading to the decrease of martensitic transformation temperature
TM in Ni
51Mn
34Co
2Sn
13 and Ni
50Mn
34Co
3Sn
13 alloys. On the other hand, the substitution of Sn for Mn atoms in Ni
50Mn
34Co
2Sn
14 would enhance the
p-d covalent hybridization between the main group element (Sn) and the transition metal element (Mn or Ni) due to the increase of Sn content, thus also reducing the
TM by stabilizing the parent phase. Due to the reduction of
TM, a magnetostructural martensitic transition from FM austenite to weak-magnetic martensite is realized in Ni
51Mn
34Co
2Sn
13 and Ni
50Mn
34Co
2Sn
14, resulting in a large magnetocaloric effect around room temperature. For a low field change of 3 T, the maximum ∆
SM reaches as high as 30.9 J/kg K for Ni
50Mn
34Co
2Sn
14. A linear dependence of Δ
SM upon
μ0H has been found in Ni
50Mn
34Co
2Sn
14, and the origin of this linear relationship has been discussed by numerical analysis of Maxwell’s relation.
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