Ab initio construction of magnetic phase diagrams in alloys: The case of Fe$_{1-x}$Mn$_x$Pt

TL;DR

This paper introduces a first-principles method for constructing magnetic phase diagrams of alloys, successfully applied to Fe$_{1-x}$Mn$_x$Pt, revealing phase sequences and predicting a new low-temperature phase.

Contribution

It presents a novel ab initio approach that accounts for complex magnetic interactions and phases in metallic alloys, improving understanding of magnetic phase diagrams.

Findings

Sequence of magnetic phases at T=0 matches experiments

Predicted a new low-temperature phase at Mn-rich end

Demonstrated the significance of non-Heisenberg interactions

Abstract

A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account for competing interactions and multiple magnetic phases. Application to the Fe$_{1-x}$Mn$_x$Pt "magnetic chameleon" system yields the sequence of magnetic phases at T=0 and the c-T magnetic phase diagram in good agreement with experiment, and a new low-temperature phase is predicted at the Mn-rich end. The importance of non-Heisenberg interactions for the description of the magnetic phase diagram is demonstrated.