Effect of Co substitution on Ni$_{2}$MnGe Heusler alloy: ab initio study

TL;DR

This study uses ab initio calculations to explore how substituting Co for Ni in Ni$_{2}$MnGe affects its structural and magnetic properties, revealing decreases in lattice constant and increases in magnetic moments.

Contribution

It provides new insights into the effects of Co substitution on the structural and magnetic properties of Ni$_{2}$MnGe Heusler alloys through detailed ab initio analysis.

Findings

Lattice constant decreases with Co substitution.

Total magnetic moment increases with Co content.

Mn(B) has the largest local magnetic moment.

Abstract

Ab initio calculations shown that the Co substitution instead of Ni in Ni$_{2}$MnGe with the L2$_{1}$ crystallographic structure leads to a decrease of the lattice constant and an increase of the total magnetic moment of the Ni$_{2-x}$Co$_{x}$MnGe compounds. The Mn(B) has the largest local moment above $3~\mu_{B}$ coupled parallel to moments on the Ni(A,C) and Co(A,C), which are found in the ranges of $0.19\div0.26~\mu_{B}$ for Ni(A,C) and $1.03\div0.97~\mu_{B}$ for Co(A,C) for studied range of $x$. Using the results stemming from the total energy calculations, the values of bulk modulus and its pressure derivatives are estimated according to the Murnaghan EOS.