Quenched crystal-field disorder and magnetic liquid ground states in Tb2Sn2−xTixO7

Solid solutions of the “soft” quantum spin ice pyrochlore magnets Tb2B2O7 with B = Ti and Sn display a novel magnetic ground state in the presence of strong B-site disorder, characterized by a low susceptibility and strong spin fluctuations to temperatures below 0.1 K. These materials have been studied using ac susceptibility and μSR techniques to very low temperatures, and time-of-flight inelastic neutron scattering techniques to 1.5 K. Remarkably, neutron spectroscopy of the Tb3+ crystal-field levels appropriate to high B-site mixing (0.5