Coexisting Charge-Ordered States with Distinct Driving Mechanisms in Monolayer VSe2

Chua, R and Henke, J and Saha, S and Huang, Y and Gou, J and He, X and Das, T and Van Wezel, J and Soumyanarayanan, A and Wee, ATS (2021) Coexisting Charge-Ordered States with Distinct Driving Mechanisms in Monolayer VSe2. In: ACS Nano .

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Abstract

Thinning crystalline materials to two dimensions (2D) creates a rich playground for electronic phases, including charge, spin, superconducting, and topological order. Bulk materials hosting charge density waves (CDWs), when reduced to ultrathin films, have shown CDW enhancement and tunability. However, charge order confined to only 2D remains elusive. Here we report a distinct charge ordered state emerging in the monolayer limit of 1T-VSe2. Systematic scanning tunneling microscopy experiments reveal that bilayer VSe2 largely retains the bulk electronic structure, hosting a tridirectional CDW. However, monolayer VSe2 -consistently across distinct substrates-exhibits a dimensional crossover, hosting two CDWs with distinct wavelengths and transition temperatures. Electronic structure calculations reveal that while one CDW is bulk-like and arises from the well-known Peierls mechanism, the other is decidedly unconventional. The observed CDW-lattice decoupling and the emergence of a flat band suggest that the second CDW could arise from enhanced electron-electron interactions in the 2D limit. These findings establish monolayer-VSe2 as a host of coexisting charge orders with distinct origins, and enable the tailoring of electronic phenomena via emergent interactions in 2D materials. © 2021 American Chemical Society.

Item Type:	Journal Article
Publication:	ACS Nano
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to American Chemical Society.
Keywords:	Charge density; Charge density waves; Electron-electron interactions; Electronic structure; Monolayers; Scanning tunneling microscopy; Transition metals; Ultrathin films, Charge ordered state; Charge-density-waves; Charge-ordering; Dichalcogenides; Driving mechanism; Electronic phasis; Thinnings; Transition metal dichalcogenides; Two dimensions (2D); Two-dimensional materials, Selenium compounds
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	07 Jan 2022 10:41
Last Modified:	07 Jan 2022 10:41
URI:	http://eprints.iisc.ac.in/id/eprint/70945

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