Revisiting the magnetic ground states of RECo$_5$ permanent magnets

TL;DR

This paper reevaluates the magnetic properties and structures of RECo$_5$ permanent magnets using recent neutron diffraction data and improved theoretical models, providing new insights into their magnetic behavior and potential for future magnet development.

Contribution

It introduces updated magnetic structure and single-ion property analyses of RECo$_5$ magnets based on recent experimental data and refined theoretical modeling.

Findings

Determined temperature-dependent magnetic moments of YCo$_5$ and NdCo$_5$.

Extracted crystal field parameters for SmCo$_5$ from neutron spectroscopy data.

Provided a comprehensive analysis that may guide future permanent magnet research.

Abstract

In light of recent improvements in the theory of rare earth magnets, as well as the availability of improved neutron powder diffraction data on these materials, we revisit the magnetic single-ion properties of SmCo$_5$ and the magnetic structures of YCo$_5$ and NdCo$_5$. From neutron diffraction patterns in a wide range of temperatures between 3 K and 800 K, we obtain the thermal coefficient expansion and the magnetic moment values for the latter two materials. For SmCo$_5$, we fit existing neutron spectroscopy data with a model recently used for NdCo$_5$ to obtain the crystal field parameters, which are essential to determine the low-lying energy scales that set the Hamiltonian. Our results may trigger new experimental and theoretical studies towards a new route for the realization of permanent magnets.