Robust Luttinger Liquid State of 1D Dirac Fermions in a Van der Waals System Nb₉Si₄Te₁₈

We report on the Tomonaga-Luttinger liquid (TLL) behavior in fully degenerate 1D Dirac Fermions. A ternary van der Waals material Nb₉Si₄Te₁₈ incorporates in-plane NbTe₂ chains, which produce a 1D Dirac band crossing Fermi energy. Tunneling conductance of electrons confined within NbTe₂ chains is found to be substantially suppressed at Fermi energy, which follows a power law with a universal temperature scaling, hallmarking a TLL state. The obtained Luttinger parameter of ∼0.15 indicates a strong electron-electron interaction. The TLL behavior is found to be robust against atomic-scale defects, which might be related to the Dirac electron nature. These findings, combined with the tunability of the compound and the merit of a van der Waals material, offer a robust, tunable, and integrable platform to exploit non-Fermi liquid physics.