Effect of lattice relaxation on magnetic anisotropy:Zr-dopedSm2Co17

Abstract

The magnetic anisotropy energy (MAE) in rare-earth/transition-metal hard magnets originates from the onsite anisotropy of the rare-earth element with additional contribution from the transition-metal sublattice. While ${\mathrm{SmCo}}_{5}$ can be transformed to ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$ by partial substitution of Sm by ${\mathrm{Co}}_{2}$ dumbbells, the MAE in ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$ is noticeably smaller compared to that in ${\mathrm{SmCo}}_{5}.$ However, small dopings of nonmagnetic Zr significantly increase the MAE in ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}.$ We show that the changes to the MAE in ${\mathrm{Sm}}_{2}{\mathrm{Co}}_{17}$ can be traced down to the reduction of the crystal field at the Sm site due to the Co sublattice relaxation upon $\mathrm{Sm}\ensuremath{\rightarrow}{\mathrm{Co}}_{2}$ substitution which is subsequently restored upon substitution of ${\mathrm{Co}}_{2}\ensuremath{\rightarrow}\mathrm{Zr}.$