Finite-temperature magnetism of Fe$_x$Pd$_{1-x}$ and Co$_x$Pt$_{1-x}$ alloys

TL;DR

This paper investigates the finite-temperature magnetic properties of FePd and CoPt alloys, emphasizing the importance of including interactions mediated by induced magnetic moments of non-magnetic atoms, and presents a computational scheme for calculating Curie temperatures that aligns well with experimental data.

Contribution

The study introduces a calculation scheme for Curie temperatures in magnetic alloys that accounts for interactions mediated by non-magnetic atoms, using ab-initio derived exchange parameters.

Findings

Calculated Curie temperatures agree well with experimental data.

Including non-magnetic atom interactions is essential for accurate magnetic behavior modeling.

The method employs the extended Heisenberg Hamiltonian with ab-initio exchange parameters.

Abstract

The finite-temperature magnetic properties of Fe$_x$Pd$_{1-x}$ and Co$_x$Pt$_{1-x}$ alloys have been investigated. It is shown that the temperature-dependent magnetic behaviour of alloys, composed of originally magnetic and non-magnetic elements, cannot be described properly unless the coupling between magnetic moments at magnetic atoms (Fe,Co) mediated through the interactions with induced magnetic moments of non-magnetic atoms (Pd,Pt) is included. A scheme for the calculation of the Curie temperature ($T_C$) for this type of systems is presented which is based on the extended Heisenberg Hamiltonian with the appropriate exchange parameters $J_{ij}$ obtained from {\em ab-initio} electronic structure calculations. Within the present study the KKR Green's function method has been used to calculate the $J_{ij}$ parameters. A comparison of the obtained Curie temperatures for Fe$_x$Pd$_{1-x}$ and Co$_x$Pt$_{1-x}$ alloys with experimental data shows rather good agreement.