Charge-density wave associated with higher-order Fermi-surface nesting in monolayer VS2

Fermi-surface (FS) nesting originating from Peierls' idea of electronic instabilities in one-dimensional materials is a key concept to stabilize charge-density wave (CDW), whereas its applicability to two-dimensional (2D) materials is under intensive debate. Here we report unusual CDW associated with the higher-order FS nesting in monolayer 2D VS2. Angle-resolved photoemission spectroscopy and scanning tunneling microscopy uncovered stripe CDW with root 21R10.9 degrees root 3R30 degrees periodicity together with an energy-gap opening on the entire FS. We suggest that this CDW involves the higher-order FS-nesting vector 2q twice larger than that of the normal one (q), as supported by the anomalies in the calculated phonon dispersion and electronic susceptibility. The present results suggest that the cooperation of q and 2q nesting leads to the fully gapped CDW state unlike the case of conventional single q nesting which produces a partial gap, pointing to an intriguing mechanism of CDW transition.

Automated summary

This study reports on the unusual charge-density wave (CDW) in monolayer 2D VS2, which is associated with higher-order Fermi-surface nesting. The CDW exhibits a stripe pattern with periodicity of root 21R10.9 degrees root 3R30 degrees and opens an energy gap on the entire Fermi surface. The results suggest the involvement of a higher-order nesting vector 2q, twice as large as the normal nesting vector q, which is supported by anomalies in the calculated phonon dispersion and electronic susceptibility.