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 Lu0.80Ho0.20Ni2 solid solution. Values of the magnetic saturation moment μs for MxHo1−xNi2 solid solutions with x⩽0.60 are close to the value of μs of undiluted HoNi2. Moreover, the value of μs 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 TC. 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.