Unconventional noncollinear magnetic order in a pyrochlore ruthenate

Frustrated pyrochlore materials have been the focus of active research in strongly correlated electron systems. Its unique geometry with spin-orbit coupling balanced by electronic correlations proposes various topological quantum phases and transitions, ranging from Weyl semimetals, quantum spin liquids, axion insulators, quadrupolar, to topological Mott insulators. While most studies so far have focused on the iridate-based pyrochlore compound at the strong spin-orbit coupling regime, much less attention was paid to weaker spin-orbit coupling materials. Here we focus on a 4d ruthenate pyrochlore with a weaker spin-orbit coupling that is generally recognised to be proximate to quantum critical points, imposing a great chance to discover unconventional magnetism.