  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.
