Antiferromagnetic Exchange Interactions in Ni$_{2}$Mn$_{1.4}$In$_{0.6}$ ferromagnetic Heusler alloy

TL;DR

This study reveals that in Ni$_{2}$Mn$_{1.4}$In$_{0.6}$ Heusler alloy, antiferromagnetic interactions originate from superexchange mechanisms involving Ni and Mn atoms, challenging the traditional view of Mn-only interactions.

Contribution

It demonstrates the role of Ni in mediating antiferromagnetic interactions via hybridization with Mn, providing new insights into magnetic coupling in Heusler alloys.

Findings

Ni contributes to magnetism through hybridization with Mn.

Antiferromagnetic moments at Ni sites are observed.

Superexchange interactions between Mn atoms are mediated by Ni.

Abstract

Magnetism in Ni-Mn-Z (Z = Ga,In,Sn,Sb) Heusler alloys has so far been predominantly attributed to Rudermann-Kittel-Kasuya-Yoshida type interactions between Mn atoms. We investigate magnetic interactions in one such alloy, Ni$_{2}$Mn$_{1.4}$In$_{0.6}$ and attempt to explain the origin of antiferromagnetic (AFM) interactions that coexist with ferromagnetic ones. Through the combination of x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD), we find that Ni plays an important role along with Mn in the overall magnetism. A significant hybridization that develops between Mn and Ni orbitals results in a small antiferromagnetic moment at Ni sites. The shift in the XMCD hysteresis loops in the martensitic phase suggests that antiferromagnetism results from superexchange like interactions between Mn atoms mediated by Ni.