Single-Particle Excitations in One-Dimensional Mott-Hubbard InsulatorNaV2O5

We have made an angle-resolved photoemission study of ${\mathrm{NaV}}_2{\mathrm{O}}_5$ at room temperature, i.e., in the paramagnetic phase well above the spin-Peierls transition temperature. The obtained results reflect the one dimensionality of the electronic structure. The lower binding energy side of the V $3d$ band shows a clear momentum-dependent modulation with the periodicity of $\pi$, indicating the existence of antiferromagnetic correlations or holon excitations in the one-dimensional Mott insulator. We compare the results with recent theoretical works on the one-dimensional Hubbard and $t$- $J$ models and discuss consistency between model parameters.