Orbital contributions to the transferred hyperfine fields in rare-earth compounds

Magnetic hyperfine fields acting on the nuclei of diamagnetic atoms in rare-earth intermetallic compounds are generally assumed to follow a form $H_{hf}=H_s(g_J-1)〈J_z〉$. However, such an expression is inadequate to describe the detailed dependence of the transferred hyperfine fields as the rare-earth ion is changed. It is shown that an expression based on a Hamiltonian which includes orbital contributions to the hyperfine field can describe the available data on several series of rare-earth compounds. This dependence has the form $H_{hf}=\left[\right(g_J-1)H_{01}+(2-g_J)H_{10}+c_n{H}_{21}]〈J_z〉$, where the $c_n$ are appropriate rare-earth reduced matrix elements. By fitting the extant data to this expression, we find that the orbital contributions H₁₀ and H₂₁ are appreciable. The general form of this expression is found to be valid for a variety of mechanisms which produce transferred and supertransferred hyperfine fields.