Observations of Charge-Density-Wave States in W 6 Te 6 Wires.

Determining the electronic ground state of a one-dimensional system is crucial to understanding the underlying physics of electronic behavior. Here, we demonstrate the discovery of charge-density wave states in few-wire W 6 Te 6 arrays using scanning tunneling microscopy/spectroscopy. We directly visualize incommensurate charge orders, energy gaps with prominent coherence peaks, and the picometer-scale lattice distortion in nearly disorder-free double-wire systems, thereby demonstrating the existence of Peierls-type charge density waves. In the presence of disorder-induced charge order fluctuations, the coherence peaks resulting from phase correlation disappear and gradually transform the system into the pseudogap states. The power-law zero-bias anomaly and quasi-particle interference analysis further suggest the Tomonaga-Luttinger liquid behavior in such pseudogap region. In addition, we explicitly determined the evolution of the CDW energy gap as a function of stacking-wire numbers. The present study demonstrates the existence of electron-phonon interactions in few-wire W 6 Te 6 that can be tuned by disorders and van der Waals stacking.