Ground state of the spin liquid candiate NaRuO2

The classic pedagogical example of geometric frustration is given on the triangular lattice, but it does not often manifest in real systems due to frustration lifting effects such as structural symmetry lowering or antisymmetric exchange interactions. When spin-orbit coupling is sufficiently strong, which is true in the 4d transition metal Ru, it is possible for magnetic frustration to manifest via off-diagonal, Kitaev-type exchange terms on a triangular lattice. In this limit, extended exchange effects also come into play as well as charge fluctuations inherent to a weak Mott state. Here we present Ru-L3 resonant inelastic X-ray scattering and magnetic measurements on the quantum spin liquid candidate NaRuO2. RIXS results suggest the ground state of NaRuO2 cannot fully described in a localised Kitaev picture and is weakly itinerant. High field magnetisation measurements are well fit to a random singlet model, suggesting the system is consistent with having a spin liquid ground state. Our results provide key insights to the ground state of the spin liquid candidate material NaRuO2.