Quantum and thermal spin relaxation in the diluted spin ice Dy2−xMxTi2O7 (M=Lu,Y)

Abstract

We have studied the low-temperature ac magnetic susceptibility of the diluted spin ice compound Dy2−xMxTi2O7, where the magnetic Dy ions on the frustrated pyrochlore lattice have been replaced with nonmagnetic ions, M=Y or Lu. We examine a broad range of dilutions, 0⩽x⩽1.98, and we find that the T∼16K freezing is suppressed for low levels of dilution but re-emerges for x>0.4 and persists to x=1.98. This behavior can be understood as a nonmonotonic dependence of the quantum spin relaxation time with dilution. The results suggest that the observed spin freezing is fundamentally a single spin process that is affected by the local environment, rather than the development of spin-spin correlations as earlier data suggested.