The magnetic instability of Yb₂Pd₂(In, Sn) in a non-fermi liquid environment

Various concentrations of the solid solution Yb₂Pd ₂In_1-xSn_x ranging from x = 0 to 1 with the tetragonal Mo₂FeB₂-type structure were prepared and their physical properties were studied by means of bulk and spectroscopic measurements as a function of temperature, pressure and magnetic fields. Results deduced from these studies indicate a slight variation of the valency of the Yb ions, from ν ≈ 2.9 for both border compounds to ν = 3 at x = 0.6. This variation gives rise to the appearance of long range magnetic order in a narrow concentration region around x = 0.6, while both border compounds remain non-magnetic. The outstanding concentration dependence for the ordered regime may be indicative of two quantum critical points, a novel feature not yet observed in Yb compounds.