Singular magnetic dilution behavior in a quasicrystal approximant

We report the effect of magnetic dilution on the physical properties of $({\mathrm{Gd}}_{1\ensuremath{-}x}{\mathrm{Y}}_x){\mathrm{Cd}}₆$ approximant crystals (ACs), close siblings of their corresponding quasicrystal (QC). Compared to the pure system ${\mathrm{GdCd}}₆$, we observe remarkable changes in the thermodynamic and magnetic bulk properties near and below the static-ordering temperatures from diluting the magnetic Gd atoms with nonmagnetic Y atoms by only 1--3% $(x=0.01--0.03)$. On the other hand, the corresponding QC system exhibits a monotonic change in its spin-glass behavior upon the magnetic dilution. We discuss the origin of the magnetic-dilution behavior in the present AC system in terms of possible magnetic frustration and short-range magnetic correlation that can be linked to its peculiar structure.