Abstract We report a systematic study on the magneto-structural transition in Mn-rich Fe-doped Mn-Fe-Ni-Sn(Sb/In) Heusler alloys by keeping the total valence electron concentration (e/a ratio) fixed. The martensitic transition (MT) temperature is found to shift by following a proportional relationship with the e/a ratio of the magnetic elements alone. The magnetic entropy change (ΔSM) across MT for a selected sample (Mn49FeNi40Sn9In) has been estimated from three different measurement methods (isofield magnetization (M) vs temperature (T), isothermal M vs field (H) and heat capacity (HC) vs T). We observed that though the peak value of ΔSM changes with the measurement methods, the broadened shape of the ΔSM–T curves and the corresponding cooling power (∼140 Jkg−1) remains invariant. The equivalent adiabatic temperature change (ΔT) ∼−2.6 K has been obtained from indirect measurements of ΔT. Moreover, an exchange bias field ∼783 Oe at 5 K and a magnetoresistance of −30% are also obtained in one of these materials.

中文翻译：

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富锰 Mn-Fe-Ni-Sn(Sb/In) Heusler 合金中与测量无关的磁热效应

摘要 我们通过保持总价电子浓度（e/a 比）固定，对富锰 Fe 掺杂 Mn-Fe-Ni-Sn(Sb/In) Heusler 合金的磁结构转变进行了系统研究。发现马氏体转变 (MT) 温度通过遵循与单独磁性元素的 e/a 比的比例关系而发生变化。已通过三种不同的测量方法（等场磁化强度 (M) 与温度 (T)、等温 M 与场 (H) 以及热容量 (HC) 与吨）。我们观察到，尽管 ΔSM 的峰值随测量方法而变化，但 ΔSM-T 曲线的加宽形状和相应的冷却功率 (~140 Jkg-1) 保持不变。等效绝热温度变化 (ΔT) ∼-2。6 K 已从 ΔT 的间接测量中获得。此外，在其中一种材料中还获得了 5 K 时的交换偏置场 ~783 Oe 和 -30% 的磁阻。