Spin-ice behavior in Dy 2 Sn 2 − x Sb x O 7 + x ∕ 2 and Dy 2 Nb Sc O 7

We report the magnetic and thermal properties of ${\mathrm{Dy}}_{2}{\mathrm{Sn}}_{2\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{O}}_{7+x∕2}$ ($x=0$, 0.25, and 0.5) and of ${\mathrm{Dy}}_{2}\mathrm{Nb}\mathrm{Sc}{\mathrm{O}}_{7}$. We find evidence for Ising-like single ion ground states in the ${\mathrm{Dy}}_{2}{\mathrm{Sn}}_{2\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{O}}_{7+x∕2}$ materials. Furthermore, these materials possess nearly the same zero-point entropy as the canonical spin ices ${\mathrm{Ho}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ and ${\mathrm{Dy}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$. These results strongly suggest that the ${\mathrm{Dy}}_{2}{\mathrm{Sn}}_{2\ensuremath{-}x}{\mathrm{Sb}}_{x}{\mathrm{O}}_{7+x∕2}$ materials studied have spin-ice states at low temperatures. We also observe a somewhat reduced zero-point entropy in ${\mathrm{Dy}}_{2}\mathrm{Nb}\mathrm{Sc}{\mathrm{O}}_{7}$, which is possibly associated with a higher level of cation disorder. The icelike states in these materials, despite the cation disorder on the $B$ sites of the pyrochlore lattice, provide evidence for the robust nature of spin-ice behavior in the presence of disorder.