Commercial magnets based on samarium and cobalt (Sm-Co) actually consist of several different crystal phases with varying chemical compositions. The bulk of the magnet is made up of Sm₂Co₁₇, but these regions are surrounded by a cell boundary phase which has a chemical composition closer to Sm(Co_1-x-yFe_xCu_y)₅. Experimental work conducted at the National Institute for Materials Science (NIMS) in Tsukuba, Japan found a link between chemical composition of this cell boundary phase and the resistance to demagnetization (coercivity) of the permanent magnet. In collaboration with Dr Munehisa Matsumoto of the University of Tokyo we have performed a computational study on the prototype cell boundary phase Y(Co_1-x-yFe_xCu_y)₅ to understand how the chemical composition (iron and copper content) affects the magnetic properties, namely the magnetic anisotropy, of the transition metal. Interestingly our work does not find large differences with different chemical composition, indicating that other factors (e.g. interface roughness or interactions involving Sm) are playing a role in commercial magnets.

Journal reference: https://doi.org/10.1016/j.jmmm.2019.01.061