Electronic structure of $2H$-NbSe${}_2$ single-layers in the CDW state

Abstract

A density functional theory study of NbSe${}_2$ single-layers in the normal non-modulated and the $3\times 3$ CDW states is reported. We show that, in the single layer, the CDW barely affects the Fermi surface of the system, thus ruling out a nesting mechanism as the driving force for the modulation. The CDW stabilizes levels lying around 1.5 eV below the Fermi level within the Se-based valence band but having a substantial Nb-Nb bonding character. The absence of interlayer interactions leads to the suppression of the pancake-like portion of the bulk Fermi surface in the single-layer. We perform scanning tunneling microscopy simulations and find that the images noticeably change with the sign and magnitude of the voltage bias. The atomic corrugation of the Se sublayer induced by the modulation plays a primary role in leading to these images, but the electronic reorganization also has an important contribution. The analysis of the variation of these images with the bias voltage does not support a Fermi surface nesting mechanism for the CDW. It is also shown that underlying graphene layers (present in some of the recent experimental work) do not modify the conduction band, but do affect the shape of the valence band of NbSe${}_2$ single-layers. The relevance of these results in understanding recent physical measurements for NbSe${}_2$ single-layers is discussed.

References in corpus (7)

• Strongly enhanced charge-density-wave order in monolayer NbSe${}_2$
• Characterization of collective ground states in single-layer NbSe2
• Controlling many-body states by the electric-field effect in a two-dimensional material
• Quality heterostructures from two dimensional crystals unstable in air by their assembly in inert atmosphere
• Enhanced superconductivity in atomically thin TaS2
• Penetration depth study of superconducting gap structure of 2\textit{H}-NbSe${}_2$
• Experimental evidence for a two-gap structure of superconducting NbSe_2: a specific heat study in external magnetic fields

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