Strain glass versus antisite disorder induced ferromagnetic state in Fe doped Ni-Mn-In Heusler martensites

TL;DR

This study explores how Fe doping in Ni-Mn-In Heusler alloys induces either a strain glassy phase or a ferromagnetic phase, depending on the doping site, revealing the roles of antisite disorder and impurity phases.

Contribution

It demonstrates how Fe doping at different lattice sites leads to distinct magnetic and structural phases, highlighting the mechanisms behind strain glass formation and ferromagnetism in Ni-Mn-In alloys.

Findings

Fe doping at Mn sites induces strain glassy phase via impurity phases.

Fe doping at Ni sites causes antisite disorder and ferromagnetism.

Impurity γ-(Fe,Ni) phase is responsible for strain glass behavior.

Abstract

Fe doping in Ni$_2$Mn$_{1.5}$In$_{0.5}$ results in suppression of the martensitic phase via two contrasting routes. In Ni$_2$Mn$_{1.5-x}$Fe$_{x}$In$_{0.5}$, the martensitic phase is converted to a strain glassy phase, while in Ni$_{2-y}$Fe$_y$Mn$_{1.5}$In$_{0.5}$, a cubic ferromagnetic phase results at the expense of the martensite. Careful studies of magnetic and structural properties reveal the presence of the impurity $\gamma -$(Fe,Ni) phase as the reason for the emergence of non-ergodic strain glassy phase when Fe is sought to be doped at Y/Z (Mn) sites of X$_2$YZ Heusler alloy. Whereas attempts to dope Fe in the X (Ni) sublattice result in an A2 type antisite disorder that promotes a ferromagnetic ground state.