Individual Co site contributions to the magnetic anisotropy ofRCo5compounds and related structures

NMR results are used to evaluate the spin-orbit contribution to the magnetic anisotropy of Co atoms at individual Co sites in $R{\mathrm{Co}}_5$ compounds. The easy $c$-axis Co anisotropy of $R{\mathrm{Co}}_5$ compounds is found to arise from the ($2c$) sites, while the ($3g$) sites make a smaller opposing contribution. The anisotropy parameters of the individual sites are used to calculate the variation of anisotropy with composition in mixed $R{\left({\mathrm{Co}}_{1-x}{\mathrm{Fe}}_x\right)}_5$ compounds and also to estimate anisotropy parameters at individual sites in some structures related to the $R{\mathrm{Co}}_5$ phase.