Structural, magnetic, and electrical properties of Li2Ir1-xRuxO3

The crystal structure, resistivity, and magnetic susceptibility of the Li2Ir1-xRuxO3 (x = 0-1) polycrystals have been investigated. We found that the parent antiferromagnetic phase disappears for x > 0.2 and bond dimers appear in the averaged structure for x > 0.5 and likely fluctuate for much smaller x. Unexpectedly, this system remains insulating for all the doping levels, contrary to the predictions based on the one-band j(eff) = 1/2 Kitaev-Heisenberg model. These results suggest that the honeycomb iridates doped with ruthenium are a unique 5d-orbital-based platform for studying the interplay of the charge, orbital, spin, and lattice degrees of freedom.