Effect of Stacking Order on the Electronic State of 1T-TaS${}_2$

Abstract

New theoretical proposals and experimental findings on transition metal dichalcogenide 1T-TaS${}_2$ have revived interests in its possible Mott insulating state. We perform a comprehensive scanning tunneling microscopy and spectroscopy experiment on different single-step areas in pristine 1T-TaS${}_2$. After accurately determining the relative displacement of Star-of-David super-lattices in two layers, we find different stacking orders can correspond to the similar large-gap spectrum on the upper terrace. When the measurement is performed away from the step edge, the large gap spectrum can always be maintained. The stacking order seems rarely disturb the large-gap spectrum in the ideal bulk material. We conclude that the large insulating gap is from the single-layer property, which is a correlation-induced Mott gap based on the single-band Hubbard model. Specific stacking orders can perturb the state and induce a small-gap or metallic spectrum for a limited area around the step edge, which we attribute to a surface and edge phenomenon. Our work provides more evidence about the surface electronic state and deepens our understanding of the Mott insulating state in 1T-TaS${}_2$.

9 pages, 8 figures

References in corpus (8)

• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Correlated electronic states at domain walls of a Mott-charge-density-wave insulator 1T-TaS2
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• Doublon-like excitations and their phononic coupling in a Mott charge-density-wave system

Cited by in corpus (18)

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• Reconcile the Bulk Metallic and Surface Insulating state in 1T-TaSe${}_2$
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• Modified interlayer stacking and insulator to correlated-metal transition driven by uniaxial strain in 1$T$-TaS${}_2$
• Charge density wave surface reconstruction in a van der Waals layered material
• Photo-induced charge dynamics in 1$T$-TaS${}_2$
• Charge-Neutral Electronic Excitations in Quantum Insulators
• Causal versus local $GW$+EDMFT scheme and application to the triangular-lattice extended Hubbard model
• Origin of Distinct Insulating Domains in the Layered Charge Density Wave Material 1T-TaS2
• Stacking-induced magnetic frustration and spiral spin liquid
• Nature of metallic and insulating domains in the CDW system 1T-TaSe2
• Interlayer Hopping between Surface Mott Insulator and Bulk Band Insulator in layered 1T-TaS_{2}
• Probing complex stacking in a layered material via electron-nuclear quadrupolar coupling
• Behavior under magnetic field of resonance at the edge of the upper Hubbard band in 1T-TaS2
• Emergent Quantum Phenomena of Noncentrosymmetric Charge-Density Wave in 1T-Transition Metal Dichalcogenides
• Topical review: the nature of the ground state and possibility of a quantum spin liquid in 1T metal dichalcogenides
• Strongly Enhanced Charge-Density Waves and Correlated Insulating State in Atomically Thin 1$T$-TaS${}_2$
• Emergent quantum phenomena in two-dimensional 1T-TaS2