Influence of grain refinement and induced crystal defects on the magnetic properties of Ni50Mn36Sn14 Heusler alloy

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 L2(1)-B2-type disordered structure to a simple cubic B2-type structure for increasing milling time. From magnetometry and Mossbauer 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.