Borderline Magnetism: How Does Adding Magnesium to Paramagnetic CeCo$_3$ Make a 450 K Ferromagnet with Large Magnetic Anisotropy?

TL;DR

This study explains how magnesium alloying transforms paramagnetic CeCo$_3$ into a high-temperature ferromagnet with significant magnetic anisotropy, using first principles electronic structure calculations.

Contribution

It reveals the microscopic mechanism behind Mg-induced ferromagnetism in CeCo$_3$, highlighting the role of Stoner physics and atomic interactions for magnetic anisotropy.

Findings

Magnesium increases the Fermi-level density of states, inducing ferromagnetism.

Both Ce and Co atoms contribute to large magnetic anisotropy.

The results suggest new pathways for designing ferromagnetic materials.

Abstract

A recent experimental study (Phys. Rev. Appl. 9, 024023, 2018) on paramagnetic CeCo$_3$ finds that Magnesium alloying induces a ferromagnetic transition with intrinsic properties large enough for permanent magnet applications. Here we explain these surprising results \textit{via} a first principles study of the electronic structure and magnetism of Magnesium-alloyed CeCo$_3$. We find the origin of this Magnesium-induced ferromagnetic transition to be Stoner physics - the substantial increase in the Fermi-level density-of-states $N(E_F)$ with Mg alloying. Our calculations suggest that both Ce and Co atoms are important for generating large magnetic anisotropy suggesting the viability of Co-3$d$, and Ce-4$f$ interaction for the generation of magnetic anisotropy in magnetic materials. These results offer a new route to the discovery of ferromagnetic materials and provide fundamental insight into the magnetic properties of these alloys