We report on the synthesis of single crystalline and polycrystalline samples of Ce3−xMgxCo9 solid solution (0≤x≲1.4) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6\textit{c} site of the CeCo3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x=0.18 and reaching a Curie temperature as high as 450\,K for x=1.35. Measurements on single crystals with x=1.34 and TC=440\,K indicate an axial magnetic anisotropy with the anisotropy field of 6\,T and a magnetization of 6\,μB/f.u. at 300\,K. Coercicity is observed in the polycrystalline samples consistent with the observed axial magnetic anisotropy. Our discovery of ferromagnetism with large axial magnetic anisotropy induced by substituting a rare-earth element by Mg is a very promising result in the search of inexpensive permanent-magnet materials and suggests other non-magnetic phases, similar to CeCo3, may also conceal nearby ferromagnetic phases.
@article{arxiv.1801.06743,
title = {Ce$_{3-x}$Mg$_x$Co$_{9}$: transformation of a Pauli paramagnet into a strong permanent magnet},
author = {Tej N. Lamichhane and Valentin Taufour and Andriy Palasyuk and Qisheng Lin and Sergey L. Bud'ko and Paul C. Canfield},
journal= {arXiv preprint arXiv:1801.06743},
year = {2018}
}