A ternary map of Ni-Mn-Ga Heusler alloys from ab initio calculations

TL;DR

This study uses first-principles calculations to map the magnetic and structural properties of Ni-Mn-Ga Heusler alloys across composition diagrams, predicting stable phases and magnetic orders with good experimental agreement.

Contribution

It provides a comprehensive ternary map of Ni-Mn-Ga alloys' phases and magnetic states based on ab initio calculations, highlighting stable structures and magnetic configurations.

Findings

Ni- and Ga-rich compositions have regular Heusler structures.

Mn-rich compositions favor inverse Heusler structures.

Magnetic phase diagrams show ferromagnetic and ferrimagnetic regions.

Abstract

In the present work, the aspects of magnetic and structural properties of Ni-Mn-Ga alloys are described in the framework of fist-principles approach and mapped into ternary composition diagrams. The stable atomic arrangement and magnetic alignment for compositions with cubic austenite and tetragonal martensite structures across phase diagrams are predicted. It is shown that Ni- and Ga-rich compositions possess the regular Heusler structure in contrast to Mn-rich compositions with inverse Heusler structure as favorable one. Compositions with unstable austenite structure are concentrated in the left and right sides of diagram whereas compositions with unstable martensite structure are located in the low-middle part of diagram. The magnetic phase diagrams showing regions with the ferromagnetic order and the complex ferrimagnetic order for austenitic and martensitic compositions are obtained. The results of calculations are in a good agreement with available experimental data.