Charge density wave, superconductivity, and anomalous metallic behavior in2D transition metal dichalcogenides

We propose a theory for quasi-two-dimensional transition metal dichalcogeni des that provides a unified microscopic picture of the charge density wave (CDW) and superconducting phases. We show, based on the electron-phonon cou pling and Fermi surface topology, that a CDW order parameter with sixfold s ymmetry and nodes (f-wave) gives a consistent description of the available experimental data. The elementary excitations in the CDW phase are Dirac el ectrons. The superconducting state has its origin on the attractive interac tion mediated by phonons. The theory predicts strong deviations from Fermi liquid theory in the CDW phase.