Calorimetric Investigation of the Hyperfine Interactions in Metallic Nd, Sm, and Dy

The specific heats of metallic Nd, Sm, and Dy have been measured in the temperature range 0.025-0.4 K, where the nuclear (hyperfine) heat capacity predominates. The data are fitted to theoretical Schottky curves corresponding to a Hamiltonian of the form $H=a^{\prime }{I}_z+P[I_z^{}{}_{}{}^2-\frac{1}{3}I(I+1\mathrm{}\left)\right]$, where $a^{\prime }$ and $P$ are the magnetic dipole and electric quadrupole interaction parameters, respectively. The Nd data are consistent with a two-sublattice model with the electronic moments on each sublattice appreciably less than the full saturation value. Both the Sm and Dy data fit Schottky anomalies corresponding to the full saturated electronic moment on each ion.