Strain Engineering a $4a\times \sqrt{3}a$ Charge Density Wave Phase in Transition Metal Dichalcogenide 1T-VSe${}_2$

Abstract

We report a rectangular charge density wave (CDW) phase in strained 1T-VSe${}_2$ thin films synthesized by molecular beam epitaxy on c-sapphire substrates. The observed CDW structure exhibits an unconventional rectangular 4a{\times}{\sqrt{3a}} periodicity, as opposed to the previously reported hexagonal $4a\times 4a$ structure in bulk crystals and exfoliated thin layered samples. Tunneling spectroscopy shows a strong modulation of the local density of states of the same $4a\times \sqrt{3}a$ CDW periodicity and an energy gap of $2{\Delta }_{CDW}=(9.1\pm 0.1)$ meV. The CDW energy gap evolves into a full gap at temperatures below 500 mK, indicating a transition to an insulating phase at ultra-low temperatures. First-principles calculations confirm the stability of both $4a\times 4a$ and $4a\times \sqrt{3}a$ structures arising from soft modes in the phonon dispersion. The unconventional structure becomes preferred in the presence of strain, in agreement with experimental findings.

References in corpus (12)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Boron nitride substrates for high-quality graphene electronics
• Strain-Engineering Anisotropic Electrical Conductance of Phosphorene and Few-Layer Black Phosphorus
• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Fermi surface nesting and the origin of Charge Density Waves in metals
• Classification of Charge Density Waves Based on Their Nature
• X-ray diffraction observation of charge density wave order at zero magnetic field in ortho-II YBa${}_2$Cu${}_3$O${}_{6.54}$
• A quantum phase transition from triangular to stripe charge order in NbSe${}_2$
• Pseudomagnetic Fields in a Locally Strained Graphene Drumhead
• Experimental evidence for a Bragg glass density wave phase in a transition-metal dichalcogenide
• Transport and Magnetic Properties of FexVse2 (x = 0 - 0.33)

Cited by in corpus (2)

• Monolayer VTe2: Incommensurate Fermi surface nesting and suppression of charge density waves
• Effect of Strain on Charge Density Wave Order in the Holstein Model