Peculiar magnetic properties of hcp Sm are adequately described by the calculations based on the model with ${\mathrm{Sm}}^{3+}$ ions in a metallic matrix, taking into account the lowest three multiplets, the spin-orbit interaction, the crystal fields, and the exchange interaction, and together with the conduction-electron spin polarization. It is found that the effect of the conduction-electron polarization is essential to them. By the analyses, it is concluded that the conduction-electron moment is larger than the localized $4f$ one and that the polarity of the spin part of the magnetic moment enhanced by the conduction-electron polarization is positive to the total moment. This polarity of the spin moment, which is opposite to the case for the free ${\mathrm{Sm}}^{3+}$ ion, is furthermore experimentally verified by the magnetic measurements on the hcp SmNd and SmGd alloys. It is also elucidated through the calculations that the difference between the temperature dependence of the spin moment and that of the orbital one due to the admixture of the $J$ multiplets, in general, results in a variety of temperature dependence of the ordered moment for each ${\mathrm{Sm}}^{3+}$ ion, just like the thermomagnetic behavior of ferrimagnets.

• Received 22 May 1996

DOI:https://doi.org/10.1103/PhysRevB.56.349