Influence of controlled disorder on the dipolar spin ice state of Ho-based pyrochlores

A three-dimensional network of corner-sharing tetrahedra, one of the canonical frustrated lattices, is realized by the rare-earth ions in a wide array of pyrochlore magnets. Ho-based systems host an exotic dipolar spin-ice ground state with Ising moments governed by the ice rules and elementary excitations resembling magnetic monopoles. Here, we investigate the effect of controlled disorder on this novel state of matter by introducing two different types of site mixing on the non-magnetic cation site. Ho₂GaSbO₇ has chemical disorder only, while Ho₂ScSbO₇ has both chemical and size disorder due to the large ionic radius difference of Sc and Sb. Although both systems are Ising pyrochlores, we find a reduced correlation length for the Ho and Sc/Sb cation ordering and evidence for enhanced local structure distortions in Ho₂ScSbO₇. Despite these significant structural differences, both systems exhibit key signatures of dipolar spin ice physics. Our results show that this magnetic ground state is extremely robust to different types of non-magnetic B-site disorder in the Ho pyrochlore family.