Influence of MNi2 (M=Sc,Y, La,Lu) compounds on the ferromagnetism of HoNi2–MNi2 solid solutions

Ferromagnetic properties of HoNi₂–MNi₂ solid solutions were studied. HoNi₂ is a typical rare earth ferromagnet with the Curie temperature equal to 17.6 K. The source of ferromagnetic order are exchange interaction between magnetic moments of holmium atoms. In the case of solid solutions HoNi₂–MNi₂ for M=Sc, Y and La, the disappearance of ferromagnetic order has been observed for concentrations of M higher than 60 atomic % whereas for the system HoNi₂–LuNi₂ the ferromagnetic order is observed even in Lu_0.80Ho_0.20Ni₂ solid solution. Values of the magnetic saturation moment μ_s for M_xHo_1−xNi₂ solid solutions with x?0.60 are close to the value of μ_s of undiluted HoNi₂. Moreover, the value of μ_s of HoNi₂ suggests that, apart from the contribution of holmium a small contribution of Ni atoms is added. The paramagnetic Curie temperatures Θ are somewhat lower than the values typical of ferromagnets: usually Θ is almost equal to T_C. Paramagnetic moments of the solid solutions are similar or higher than that found for pure HoNi₂. On the basis of the results obtained one may have to state that the influence of the LuNi₂ is the weakest and this compound may be regarded as the best diluter and, in the case of heat capacity measurements, also as the best reference material.