Putative spin liquid in the triangle-based iridate Ba₃IrTi₂O₉

We report on thermodynamic, magnetization, and muon spin relaxation measurements of the strong spin-orbit coupled iridate Ba3IrTi2O9, which constitutes a distinct frustration motif made up of a mixture of edge- and corner-sharing triangles. In spite of a strong antiferromagnetic exchange interaction of the order of 100 K, we find no hint for long-range magnetic order down to 23 mK. The magnetic specific heat data unveil T-linear and T-squared dependences at low temperatures below 1 K. At the respective temperatures, the zero-field muon spin relaxation features a persistent spin dynamics, indicative of unconventional low-energy excitations. A comparison to the 4d isostructural compound Ba3RuTi2O9 suggests that a concerted interplay of compasslike magnetic interactions and frustrated geometry promotes a dynamically fluctuating state in a triangle-based iridate