Slow and static spin correlations in Dy2 + xTi2 − xO7 − δ

The static and dynamic spin correlations in the spin ices Dy{sub 2.3}Ti{sub 1.7}O{sub 6.85} and Dy{sub 2}Ti{sub 2}O{sub 7} have been studied in polarized neutron diffraction and neutron spin echo experiments. The measurements reveal that, below 100 mK, the magnetic scattering braodens and shifts to higher |Q| upon stuffing the pyrochlore lattice with additional Dy{sup 3+} ions. These observations can be related, by means of reverse Monte Carlo simulation, to the modified distribution of near-neighbour distances and an overall more antiferromagnetic character of the near-neighbour couplings. The dynamic measurements show that the spin correlations are slower in the stuffed system. These results will be discussed and compared to the holmium analogues.