Exchange interactions and Curie temperature of Ce-substituted SmCo5

TL;DR

This study investigates how Ce substitution affects the magnetic properties of SmCo5, revealing that tensile strain enhances Curie temperature despite Ce's negative impact on it, using mean-field approximation.

Contribution

It provides a quantitative analysis of the relationship between Ce substitution, strain, and Curie temperature in SmCo5, highlighting the role of exchange interactions.

Findings

Ce-induced tensile strain increases Curie temperature.

Ce substitution reduces Curie temperature directly.

Strain enhances ferromagnetic exchange energy.

Abstract

A partial substitution of Sm by Ce can have drastic effects on the magnetic performance, because it will introduce strain in the structure and breaks the lattice symmetry in a way that enhances the contribution of the Co atoms to magnetocrystalline anisotropy. However, Ce substitutions, which are benefit to improve the magnetocrystalline anisotropy, are detrimental to enhance the Curie temperature (TC). With the requirements of wide operating temperature range of magnetic devices, it is important to quantitatively explore the relationship between the TC and ferromagnetic exchange energy. In this paper we show, based on mean-field approximation, that Ce substitution-induced tensile strain in SmCo5 leads to enhanced effective ferromagnetic exchange energy and TC while Ce atom itself reduces TC.