Interpretation of the magnetic properties of pseudobinarySm2(Co,M)17compounds. II. Magnetization

The data available from paper I of this series offer the opportunity to ascertain the cause of the variations in both ${\mathrm{Sm}}^{3+}$ and transition-metal magnetic moments upon substitution of Co by Fe, Mn, and Cr in ${\mathrm{Sm}}_2$ ${\mathrm{Co}}_{17}$. The exchange- and crystal-field parameters derived from the magnetocrystalline anisotropy are used in the calculation of the ${\mathrm{Sm}}^{3+}$ ionic moment in fields of hexagonal symmetry. Both the moment reduction at O K and the change in the temperature at which the moment changes sign are found to agree well with the values observed experimentally. The ${\mathrm{Sm}}^{3+}$ ion changes to an $L+S$ type ion at higher temperatures but not at absolute zero. The itinerant-electron moment varies in a manner indicative of electron donation to $3d$ band in the presence of virtual bound states. The ${\mathrm{Sm}}_2$ ${\mathrm{Co}}_{17}$ crystal structure becomes unstable at high $3d$-electron concentrations.