Dimensional crossover and symmetry transformation of the charge density waves in VSe2

Abstract

Collective phenomena in solids can be sensitive to the dimensionality of the system; a case of special interest is VSe2, which shows a (r7 x r3) charge density wave (CDW) in the single layer with the three-fold symmetry in the normal phase spontaneously broken, in contrast to the (4 x 4) in-plane CDW in the bulk. Angle-resolved photoemission spectroscopy (ARPES) from VSe2 ranging from a single layer to the bulk reveals the evolution of the electronic structure including the Fermi surface contours and the CDW gap. At a thickness of two layers, the ARPES maps are already nearly bulklike, but the transition temperature TC for the (4 x 4) CDW is much higher than the bulk value of 110 K. These results can be understood as a result of dimensional crossover of phonon instability driven by a competition of nesting vectors. Our study provides key insights into the CDW mechanisms and offers a perspective in the search and control of emergent phases in quantum materials.

References in corpus (6)

• Quantum Spin Hall Effect and Topological Field Effect Transistor in Two-Dimensional Transition Metal Dichalcogenides
• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
• Pseudogap and charge density waves in two dimensions
• Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2
• Strain Engineering a $4a\times \sqrt{3}a$ Charge Density Wave Phase in Transition Metal Dichalcogenide 1T-VSe${}_2$