NMR study of Na3−xRu4O9 Original Research Article

Low-dimensional conductor Na3−xRu4O9 has been studied by means of 23Na nuclear magnetic resonance measurement in order to clarify the electronic state of this compound. The magnetic susceptibility χ is almost constant from 100 to 300 K, then increases with temperature, and shows a kink at 584 K. The temperature dependence of the Knight shift K is almost in proportion to χ. From the result of the temperature dependence of spin–lattice relaxation time, it has been found that this compound has an energy gap, Δ, which is closely correlated with the gap-like behavior of χ. Consequently, we consider that there exists a spin-singlet state in all or a part of RuO6 chains in Na3−xRu4O9.