Ruthenium Substitution in Beta-Lithium Iridate*

In the Kitaev model, orthogonal bond-directional exchange interactions have been proposed to give rise to quantum spin liquid ground state with fractional Majorana excitations. However, the candidate honeycomb materials described by this model order at low temperatures. Nonetheless, external perturbations, such as applied magnetic field, pressure, and chemical substitution, have been shown to change the strengths of the magnetic interactions and alter their ground state. Additionally, recent work in beta-lithium iridate has shown a hidden magnetic anomaly at T~100K which may be connected to the Kitaev-like behavior in the material. In this work, we present thermodynamic, resonant X-ray diffraction, and muon spin relaxation studies on ruthenium-doped beta-lithium iridate (β-Li₂Ru_xIr_1-xO₃). We describe how the addition of magnetic impurities on the iridium sites suppresses the incommensurate phase and gives rise to an anisotropic spin glass. Additionally, we discuss the impact that these impurities have on the high-temperature phase.