Magnetic Properties of 4f-3d Intermetallics Studied by $\text{}^{161}$Dy and $\text{}^{57}$Fe Mössbauer Effect

Applications of the Mössbauer effect at the $\text{}^{161}$Dy and $\text{}^{57}$Fe nuclei to study heavy rare earth - transition metal compounds are presented. Magnetic hyperfine fields at dysprosium and iron nuclei observed in the Dy$\text{}_{u}$(M-M)$\text{}_{v}$ intermetallics (u/v=2/17, 6/23, 1/3, and 1/2; M-M = Mn-Fe, Fe-Co, and Co-Ni), magnetic moments and magnetic ordering temperatures are discussed. The magnetic hyperfine field at iron nuclei and the field at dysprosium nuclei treated as functions of a number of 3d electrons form two different systems of the Slater-Pauling curves. The magnetic ordering temperatures treated as functions of the number of 3d electrons also form the u/v system of curves. Considering the magnetic data and the magnetic hyperfine fields it can be concluded that intermetallics can be treated as three-subsystem ferrimagnets. Consequently, a coexistence between the 4f, 5d, and 3d magnetism in the rare earth - transition metal compounds can be qualitatively explained.