Importance of site occupancy and absence of strain glassy phase in Ni sub(2-x)Fe sub(x)Mn sub(1.5)In sub(0.5)

Abstract

Martensitic transition temperature steadily decreases in Ni sub(2-x)Fe sub(x)Mn sub(1.5)In sub(0.5) and is completely suppressed at x = 0.2. Despite suppression of martensitic transition, Ni sub(1.8)Fe sub(0.2)Mn sub(1.5)In sub(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 sub(2)Mn sub(1−y)Fe sub(y)In sub(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.