Does the temperature dependence at constant volume of the hyperfine field of heavy impurities in ferromagnetic metals depend explicitly upon the amplitude of lattice vibrations?

Lattice dynamics seem to have little effect on the temperature dependence of the hyperfine field of pure iron and nickel and of most impurities in these metals but it is shown that Au in iron may be an exception to this rule. The hyperfine fields of other heavy impurities (FeRu,FeIr,NiPt) were found to have a normal temperature dependence.