Discovering a Wigner-like crystal and soft x-ray correlated plasmons and their couplings in a transition metal dichalcogenide

Low-dimensional systems host many exotic physical properties. Using extended resonant soft x-ray scattering supported with theoretical calculations, we observe concomitantly a Wigner-like crystal in a stripe-like Q_HKL = (001) superlattice with surprisingly long coherence lengths and new soft x-ray correlated plasmons in WS₂. A new electronic transition is found at 125 K upon cooling, which is a transition from two-dimensional ordering to three-dimensional ordering, a result of p-d hybridization anisotropy and electronic correlations. Our result shows the importance of the interplay of long-range electron-electron correlation and short-range electronic screening in determining electronics and optical properties of transition metal dichalcogenides.