Effect of Al and Si substitutions on the magnetic properties of SmTbFe17.

The structural and magnetic properties of SmTbFe_17-xAl_x (x=0–8) and SmTbFe_17-xSi_x (x=0–3.5) were investigated by x-ray-diffraction and magnetization studies. All the compounds stabilize in rhombohedral structure. The lattice parameters are found to increase with Al substitution whereas they are found to decrease with Si substitution. The rates of the decrease of saturation magnetization (M_s) value with the substitution of Al and Si are almost the same. The easy direction of magnetization (EMD) is in the ab plane up to an Al concentration of x=7 and has a tendency to shift towards the c axis at x=8. All the compounds with Si are seen to have the EMD in the ab plane. Electron-magnon scattering is seen to contribute to the electrical resistivity in both Al- and Si-substituted compounds; in the temperature range of 30–60 K and at higher temperatures, scattering due to phonons is observed. [ABSTRACT FROM AUTHOR]