Conduction-electron spin and orbital polarization effects in rare-earthAl2compounds

Nuclear magnetic resonance of the rare-earth nuclei in rare-earth ${\mathrm{Al}}_2$ compounds ($R=\mathrm{N}\mathrm{d},\mathrm{D}\mathrm{y},\mathrm{T}\mathrm{b},\mathrm{E}\mathrm{r}$) is reported. Separation of the hyperfine field into its various components is made and we deduce the variation of the self-polarization field with rare earth. The observed behavior indicates strong dependence on rare-earth orbital moment, this is accounted for including both spin and orbital polarization of the conduction bands. From comparison with the transferred hyperfine field at the Al nuclei we conclude that the orbital polarization does not extend to these sites. The consequences of these results in terms of the magnetic coupling in $R$ ${\mathrm{Al}}_2$ compounds are considered.