Ferromagnetic interactions and martensitic transformation in Fe doped Ni-Mn-In shape memory alloys

TL;DR

This study investigates how Fe doping influences the magnetic, structural, and martensitic properties of Ni-Mn-In shape memory alloys, revealing ferromagnetic interactions and structural disorder suppress martensitic transformation.

Contribution

It provides new insights into the effects of Fe doping on the phase stability and magnetic interactions in Ni-Mn-In alloys, highlighting the suppression of martensitic transformation due to ferromagnetic interactions and structural disorder.

Findings

Fe doping induces ferromagnetism in Ni-Mn-In alloys.

Martensitic transformation temperature varies with Fe concentration.

Fe doping leads to coexistence of cubic and tetragonal phases.

Abstract

The structure, magnetic and martensitic properties of Fe doped Ni-Mn-In magnetic shape memory alloys have been studied by differential scanning calorimetry, magnetization, resistivity, X-ray diffraction (XRD) and EXAFS. While Ni$_{2}$MnIn$_{1-x}$Fe$_{x}$ ($0 \le x \le 0.6$) alloys are ferromagnetic and non martensitic, the martensitic transformation temperature in Ni$_{2}$Mn$_{1.5} $In$_{1-y}$Fe$_{y}$ and Ni$_{2}$Mn$ _{1.6} $In$_{1-y}$Fe$_{y}$ increases for lower Fe concentrations ($y \le 0.05$) before decreasing sharply for higher Fe concentrations. XRD analysis reveals presence of cubic and tetragonal structural phases in Ni$_{2}$MnIn$_{1-x}$Fe$_{x}$ at room temperature with tetragonal phase content increasing with Fe doping. Even though the local structure around Mn and Ni in these Fe doped alloys is similar to martensitic Mn rich Ni-Mn-In alloys, presence of ferromagnetic interactions and structural disorder induced by Fe affect Mn-Ni-Mn antiferromagnetic interactions resulting in suppression of martensitic transformation in these Fe doped alloys.