The influence of the Mn substitution by Fe atoms on the magnetocaloric and magnetic properties of the martensitic Ni50Mn36Sn14 Heusler-type compound has been investigated using magnetization measurements. The insertion of Fe atoms reduces the Mn-Mn AF interactions resulting in (i) a systematic decrease in the martensitic transition temperature, down to its disappearance at 15 at. % of Fe, (ii) an enhancement of the saturation magnetization, and (iii) a monotonic increase in the L21-type phase Curie temperature. The Fe substitution also induces metamagnetic transition from an incipient AF to a noncollinear spin configuration for applied magnetic fields higher than 3 T in the case of 3 and 7 at. % Fe substitutional. The exchange-bias effect is only found in compounds with a well-defined martensitic phase transition (Fe content lower than 10 at. %). The maximum of the inverse magnetic entropy change, for a field variation of 5 T, is about +12 J kg−1 K−1 and it is nearly constant for Fe content up to 7 at. %. This observation suggests that the Ni50(Mn1−xFex)36Sn14 Heusler-type compounds could be used to prepare composites with potential for technological application in magnetic refrigerators.

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The effect of high energy ball milling on the structural, magnetic and magnetocaloric properties of Ni50Mn36Sn14 Heusler-type alloy has been studied. X-ray diffraction results have revealed a reduction in the crystalline grain size concomitantly with defect inclusions in the crystalline lattice, favouring a chemical disorder effect that transforms the L21–B2-type disordered structure to a simple cubic B2-type structure for increasing milling time. From magnetometry and Mössbauer spectroscopy results, a decrease in the ferromagnetic exchange interaction contribution, an enhancement of the effective exchange bias field and a significant reduction in the magnetic entropy change of the milled alloy are observed.

Cr& "Fe"alloy films ( =-3000 A) were prepared by thermal coevaporation at room temperature at a deposition rate of 25 A/min. It was found that a pure amorphous phase can be obtained in the composition range 0.25 & x &0.60, while out of this range the bcc crystalline phase appears. The structural characterization and the magnetic properties were studied by x-ray diffraction and Mossbauer spectroscopy, respectively. The crystallization temperature for an amorphous Cr&OFe30 film was found to be about 630 K as determined by in situ Mossbauer measurements. Since Cr-Fe is not a ready-glass-forming system, the amorphization process was discussed through the thermodynamics of the system and the kinetics of the condensation process.

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