Muon spin rotation study of spin dimers on a triangular lattice in Ba3MRu2O9.

The family of hexagonal perovskites, Ba3MA2O9 has recently been proven to be fertile ground for the discovery of new, exotic magnetic phases, including several quantum spin liquid candidates. The 6H-perovskites can also accommodate spin dimers on a triangular lattice, as in the ruthenate materials Ba3MRu2O9. We will present measurements on materials containing M3$+$ (M $=$ Y, La, Lu, In), which give rise to mixed valence Ru4.5$+$ ions wherein the orbital and charge degrees of freedom must also be considered. In particular, muon spin rotation (\textmu SR) experiments, have allowed us to probe the nature of the magnetically ordered ground state of these materials at low temperatures.