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

Abstract

The effect of high energy ball milling on the structural, magnetic and magnetocaloric properties of Ni 50 Mn 36 Sn 14 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 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.