Magnetism: the Driving Force of Order in CoPt. A First-Principles Study

TL;DR

This study uses first-principles calculations to demonstrate that magnetism significantly enhances the chemical ordering in CoPt alloys, revealing a strong interplay between magnetic states and structural stability.

Contribution

It provides the first ab initio analysis of how magnetism influences the stability of different structural phases in CoPt alloys.

Findings

Magnetism reinforces ordering tendencies in CoPt alloys.

Magnetic states affect the stability of L10 and L12 structures.

A tight-binding model explains the magnetic influence on ordering.

Abstract

CoPt or FePt equiatomic alloys order according to the tetragonal L10 structure which favors their strong magnetic anisotropy. Conversely magnetism can influence chemical ordering. We present here {\it ab initio} calculations of the stability of the L10 and L12 structures of Co-Pt alloys in their paramagnetic and ferromagnetic states. They show that magnetism strongly reinforces the ordering tendencies in this system. A simple tight-binding analysis allows us to account for this behavior in terms of some pertinent parameters.