Robust ferromagnetism in the compressed permanent magnetSm2Co17

Abstract

The compound ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$ displays magnetic properties amenable to permanent magnet applications owing to both the $3d$ electrons of Co and the $4f$ electrons of Sm. The long-standing description of the magnetic interactions between the Sm and Co ions implies a truly ferromagnetic configuration, but some recent calculations challenge this axiom, suggesting at least a propensity for ferrimagnetic behavior. We have used high-pressure synchrotron x-ray techniques to characterize the magnetic and structural properties of ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$ to reveal a robust ferromagnetic state. The local Sm moment is at most weakly affected by compression, and the ordered moments show a surprising resilience to volumetric compressions of nearly 20%. Density functional theory calculations echo the magnetic robustness of ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$.