Effect of Fe substitution at the Ni and Mn sites on the magnetic properties of Ni50Mn35In15 Heusler alloys

The structural and magnetic properties of Ni48Fe2Mn35In15 and Ni50Mn34FeIn15 Heusler alloys have been investigated. At room temperature, Ni48Fe2Mn35In15 has L21 cubic structure, whereas Ni50Mn34FeIn15 shows a two-phase structure due to the martensitic transition. In the case of Ni48Fe2Mn35In15, there is only one magnetic transition at 316 K with no martensitic transition. However, in Ni50Mn34FeIn15, we observe the martensitic transition at about 280 K. The Curie temperatures for austenite and martensite phases are 314 and 200 K, respectively. The maximum magnetic entropy changes are found to be 5.5 and 4.5 J kg−1 K−1 for Ni48Fe2Mn35In15 and Ni50Mn34FeIn15, respectively, for 50 kOe. Ni50Mn34FeIn15 exhibits exchange bias behavior, with a bias field of 130 Oe at 5 K. Both the alloys satisfy the empirical relation between the martensitic transition and the valence electron concentration (e/a) ratio.