Magnetism in quasibinary systems based on the valence-unstable compound CeNi

Magnetic ordering in solid solutions of Ce _x (Gd,Pr,Nd,La)_1-x Ni is studied by measuring the DC magnetization and the AC susceptibility in the temperature range of 1.8–300 K. The valence state of ceriumions in Ce _x (Gd,Pr,Nd,La)_1-x Ni quasibinary systems is studied based on X-ray absorption spectra measured at synchrotron-radiation sources in the temperature range of 5–300 K. It is shown that chemical pressure and lowering the temperature help heighten the degree of delocalization of the 4f electrons of cerium in Cex(Gd, Nd, Pr)_1-x Ni systems. It is found that the substitution of magnetic ions (Gd, Pr, and Nd) with cerium results in significantly weaker magnetic-ordering suppression than the substitution of these ions with lanthanum at equal concentrations. The obtained data reveal the strong influence of cerium electrons on localized magnetism in the studied compounds. This effect is most probably associated with the contribution of partially delocalized 4f electrons of cerium to the exchange interaction.