Mottness versus unit-cell doubling as the driver of the insulating state in 1T-TaS2

Abstract

If a material with an odd number of electrons per unit cell turns out to be insulating, Mott localisation may be invoked as an explanation. This is widely accepted for the layered compound 1T-TaS2, which has a low-temperature insulating phase comprising charge order clusters with 13 unpaired orbitals each. But if the stacking of layers doubles up the unit cell to include an even number of orbitals, the nature of the insulating state is ambiguous. Here, scanning tunnelling microscopy (STM) reveals two distinct terminations of the charge order in 1T-TaS2, the sign of such a double-layer stacking pattern. However, spectroscopy at both terminations allows us to disentangle unit-cell doubling effects and determine that Mott localisation alone is enough to drive gap formation. We also observe the collapse of Mottness at an extrinsically restacked termination, demonstrating that the microscopic mechanism of insulator-metal transitions lies in degrees of freedom of interlayer stacking.

arXiv comment9 pages, 6 figures, including Supplementary Information

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Cited by in corpus (69)

• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe2 and 1T-NbSe2
• Direct identification of Mott Hubbard band pattern beyond charge density wave superlattice in monolayer 1T-NbSe2
• Distinguishing a Mott Insulator from a Trivial Insulator with Atomic Adsorbates
• Roles of the Narrow Electronic Band near the Fermi Level in 1T-TaS${}_2$-Related Layered Materials
• Effect of Stacking Order on the Electronic State of 1T-TaS${}_2$
• Charge density wave instability and pressure-induced superconductivity in bulk 1T-NbS2
• Electrical switching of ferro-rotational order in nano-thick 1T-TaS${}_2$ crystals
• Identification of the Mott insulating CDW state in 1T-TaS${}_2$
• Mott versus hybridization gap in the low-temperature phase of $1T$-TaS${}_2$
• Mott insulator tuning via structural distortion in monolayer 1T-NbSe2
• Inducing and tuning Kondo screening in a narrow-electronic-band system
• Nonconventional screening of Coulomb interaction in two-dimensional semiconductors and metals: A comprehensive cRPA study of MX2 (M=Mo, W, Nb, Ta; X=S, Se, Te)
• Magnetic Impurity as a Local Probe of the U(1) Quantum Spin Liquid with Spinon Fermi Surface
• Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor
• Photo-induced nonequilibrium states in Mott insulators
• van der Waals heterostructures based on atomically-thin superconductors
• $\text{Ab initio}$ theory of magnetism in two-dimensional $1T$-TaS${}_2$
• Spin-orbit and exchange proximity couplings in graphene/1T-TaS${}_2$ heterostructure triggered by a charge density wave
• Reconcile the Bulk Metallic and Surface Insulating state in 1T-TaSe${}_2$
• Probing quantum spin liquids with a quantum twisting microscope
• Fractionalization on the Surface: Is Type-II Terminated $1T$-TaS${}_2$ Surface an Anomalously Realized Spin Liquid?
• Stacking effect and Coulomb correlation in layered charge density wave phase of 1T-NbS2
• Modified interlayer stacking and insulator to correlated-metal transition driven by uniaxial strain in 1$T$-TaS${}_2$
• Doublon-like excitations and their phononic coupling in a Mott charge-density-wave system
• Photo-induced charge dynamics in 1$T$-TaS${}_2$
• Charge density wave surface reconstruction in a van der Waals layered material
• Honeycomb-Lattice Mott insulator on Tantalum Disulphide
• Observation of a multitude of correlated states at the surface of bulk 1T-TaSe${}_2$ crystals
• Charge order with unusual star-of-David lattice in monolayer NbTe2
• Electronic Density of States of a $U\left(1\right)$ Quantum Spin Liquid with Spinon Fermi Surface. I. Orbital Magnetic Field Effects
• Understanding the flat band in 1T-TaS2 using a rotated basis
• Electronic Density of States of a $U\left(1\right)$ Quantum Spin Liquid with Spinon Fermi Surface. II. Zeeman Magnetic Field Effects
• Signature of Orbital Driven Finite Momentum Pairing in a 3D Ising Superconductor
• Mobile Kink Solitons in a Van der Waals Charge-Density-Wave Layer
• Origin of Distinct Insulating Domains in the Layered Charge Density Wave Material 1T-TaS2
• Coexistence of interacting charge density waves in a layered semiconductor
• Engineering Interlayer Hybridization in Energy Space via Dipolar Overlayers
• Spectroscopic evidence for possible quantum spin liquid behavior in a two-dimensional Mott insulator
• Distinguishing and controlling Mottness in 1T-TaS${}_2$ by ultrafast light
• Nature of metallic and insulating domains in the CDW system 1T-TaSe2
• Identification of soft modes across the commensurate-to-incommensurate charge density wave transition in 1$T$-TaSe${}_2$
• Observation and manipulation of a phase separated state in a charge density wave material
• Orbital textures and evolution of correlated insulating state in monolayer 1T phase transition metal dichalcogenides
• Thickness dependent charge density wave networks on thin 1T-TaS${}_2$
• Lattice-Driven Chiral Charge Density Wave State in 1T-TaS${}_2$
• Direct evidence of intrinsic Mott state and its layer-parity oscillation in a breathing kagome crystal down to monolayer
• Interlayer Hopping between Surface Mott Insulator and Bulk Band Insulator in layered 1T-TaS_{2}
• Momentum-Resolved Fingerprint of Mottness in Layer-Dimerized Nb${}_3$Br${}_8$
• Universal excitonic superexchange in spin-orbit-coupled Mott insulators
• 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
• Hidden electronic phase in strained few-layer 1T-TaS2
• Unconventional orbital-charge density wave mechanism in transition metal dichalcogenide 1T-TaS2
• Charge Density Waves in the 2.5-Dimensional Quantum Heterostructure
• Quantum Phases and Spin Liquid Properties of 1T-TaS2
• From strong to weak correlations in breathing-mode kagome van der Waals materials: Nb${}_3$(F,Cl,Br,I)${}_8$ as a robust and versatile platform for many-body engineering
• 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
• Nanoscale Modulation of Flat Bands via Controllable Charge-Density-Waves Defects in 4Hb-TaS2
• Charge-Density-Wave Oscillator Networks for Solving Combinatorial Optimization Problems
• Effect of Interlayer Stacking on the Electronic Properties of 1$T$-TaS${}_2$
• Van der Waals devices for surface-sensitive experiments
• Dynamical control of Coulomb interactions and Hubbard bands in monolayer 1T-TaS${}_2$
• Non-local optical response of a multi-phased quantum material
• Strongly Enhanced Charge-Density Waves and Correlated Insulating State in Atomically Thin 1$T$-TaS${}_2$
• Emergent quantum phenomena in two-dimensional 1T-TaS2
• Ultrafast Electronic Structure Engineering in 1$T$-TaS${}_2$: Role of Doping and Amplitude Mode Dynamics
• Scanning tunneling microscopy study of hidden phases in atomically thin 1T-TaS${}_2$