Importance of site occupancy and absence of strain glassy phase in Ni2−Fe Mn1.5In0.5

Martensitic transition temperature steadily decreases in Ni$_2-x$Fe$_x$Mn$_1.5$In$_0.5$ and is completely suppressed at $x$ = 0.2. Despite suppression of martensitic transition, Ni$_1.8$Fe$_0.2$Mn$_1.5$In$_0.5$ does not display the expected strain glassy phase. Instead, a ground state with dominant ferromagnetic interactions is observed. A study of structural and magnetic properties of $x$ = 0.2 reveal that the alloy consists of a major Fe rich cubic phase and a minor Fe deficient monoclinic phase favoring a ferromagnetic ground state. This is exactly opposite of that observed in Ni$_2$Mn$_1-y$Fe$_y$In$_0.5$ wherein a strain glassy phase is observed for $y$ = 0.1. The change in site symmetry of Fe when doped for Ni in contrast to Mn in the Heusler composition seems to support the growth of the ferromagnetic phase.