Electronic structure of single layer 1T-NbSe2: interplay of lattice distortions, non-local exchange, and Mott–Hubbard correlations

  title={Electronic structure of single layer 1T-NbSe2: interplay of lattice distortions, non-local exchange, and Mott–Hubbard correlations},
  author={Ebad Kamil and Jan Berges and Gunnar Sch{\"o}nhoff and Malte R{\"o}sner and Malte Sch{\"u}ler and Giorgio Sangiovanni and Tim Oliver Wehling},
  journal={Journal of Physics: Condensed Matter},
Using ab initio calculations we reveal the nature of the insulating phase recently found experimentally in monolayer 1T-NbSe2. We find soft phonon modes in a large part of the Brillouin zone indicating the strong-coupling nature of a charge-density-wave instability. Structural relaxation of a supercell reveals a Star-of-David reconstruction with an energy gain of 60 meV per primitive unit cell. The band structure of the distorted phase exhibits a half-filled flat band which is associated with… 

Direct identification of Mott Hubbard band pattern beyond charge density wave superlattice in monolayer 1T-NbSe2

Scanning tunneling microscopy/spectroscopy is utilized to investigate monolayer 1T-NbSe 2 to elucidate the energy of the Mott upper Hubbard band (UHB), and reveal that the spin-polarized UHB is spatially distributed away from the dz 2 orbital at the center of the CDW unit.

Charge density wave and spin 1/2 insulating state in single layer 1T-NbS2

In bulk samples and few layer flakes, the transition metal dichalcogenides NbS2 and NbSe2 assume the H polytype structure with trigonal prismatic coordination of the Nb atom. Recently, however,

Probing the interlayer coupling in 2$H$-NbS$_2$ via soft x-ray angle-resolved photoemission spectroscopy

(Dated: In the large family of two-dimensional (2D) layered materials including graphene, its honeycomb analogs, and transition-metal dichalcogenides, the interlayer coupling plays a rather

Robust charge-density wave strengthened by electron correlations in monolayer 1T-TaSe2 and 1T-NbSe2

The enhanced Mott-Hubbard and CDW gaps for monolayer TaSe2 compared to NbSe2, originating in the lattice distortion assisted by strengthened correlations and disappearance of interlayer hopping, suggest stabilization of a likely nonmagnetic CDW-Mott insulator phase well above the room temperature.

Magnetic order in a coherent two-dimensional Kondo lattice

Kondo lattices are ideal testbeds for the exploration of heavy-fermion quantum phases of matter. While our understanding of Kondo lattices has traditionally relied on complex bulk f -electron

Unified picture of lattice instabilities in metallic transition metal dichalcogenides

Transition metal dichalcogenides (TMDs) in the 1T polymorph are subject to a rich variety of periodic lattice distortions, often referred to as charge-density waves (CDWs) when not too strong. We

Strain-induced stripe phase in charge-ordered single layer NbSe2

Charge density waves are ubiquitous phenomena in metallic transition metal dichalcogenides. In NbSe2, a triangular 3 × 3 structural modulation is coupled to a charge modulation. Recent experiments

Deconfinement of Mott localized electrons into topological and spin–orbit-coupled Dirac fermions

The interplay of electronic correlations, spin–orbit coupling and topology holds promise for the realization of exotic states of quantum matter. Models of strongly interacting electrons on honeycomb

Phase‐Dependent Band Gap Engineering in Alloys of Metal‐Semiconductor Transition Metal Dichalcogenides

Bandgap engineering plays a critical role in optimizing the electrical, optical and (photo)‐electrochemical applications of semiconductors. Alloying has been a historically successful way of tuning

Topical review: recent progress of charge density waves in 2D transition metal dichalcogenide-based heterojunctions and their applications

The interplay between CDW patterns and the related unique electronic phenomena (superconductivity, spin, and Mottness) is elucidated and various manipulation methods such as doping, applying strain, local voltage pulse to induce the CDW change are discussed.



Ab initio calculations of quasiparticle band structure in correlated systems: LDA++ approach

We discuss a general approach to a realistic theory of the electronic structure in materials containing correlated $d$ or $f$ electrons. The main feature of this approach is the taking into account

Local-density functional and on-site correlations: The electronic structure of La2CuO4 and LaCuO3.

This work presents the method which delivers the correct insulating antiferromagnetic ground state in the correlated oxides preserving other properties as well as the efficiency of the standard LDA, and compares results with the standard local spin density approximation calculation and multiband Hubbard model calculations.

Monolayer 1T-NbSe2 as a Mott insulator

The emergence of exotic quantum phenomena is often triggered by a subtle change in the crystal phase. Transition metal dichalcogenides (TMDs) exhibit a wide variety of novel properties, depending on

Zone-center phonons of bulk, few-layer, and monolayer 1 T − TaS 2 : Detection of commensurate charge density wave phase through Raman scattering

We present first-principles calculations of the vibrational properties of the transition metal dichalcogenide 1T-TaS$_2$ for various thicknesses in the high-temperature (undistorted) phase and the

Strongly enhanced charge-density-wave order in monolayer NbSe2.

A combined optical and electrical transport study on the many-body collective-order phase diagram of NbSe2 down to a thickness of one monolayer opens up a new window for search and control of collective phases of two-dimensional matter, as well as expanding the functionalities of these materials for electronic applications.

Three-dimensional metallic and two-dimensional insulating behavior in octahedral tantalum dichalcogenides

Using density functional theory with added on-site interactions (DFT+U), we study the electronic structure of bulk, monolayer, and bilayer of the layered transition-metal dichalcogenide $1T-TaS_2$.

Gate-induced superconductivity in atomically thin MoS2 crystals.

A clear transition for all thicknesses down to the ultimate atomic limit is observed, providing the first demonstration of gate-induced superconductivity in atomically thin exfoliated crystals, and the superconducting properties exhibit a pronounced reduction in TC and BC when going from bilayers to monolayers.

The Perdew-Burke-Ernzerhof exchange-correlation functional applied to the G2-1 test set using a plane-wave basis set.

A plane-wave-based algorithm was implemented in VASP (Vienna ab-initio simulation package) to allow for the calculation of the exact exchange of exact exchange and hybrid functionals, with excellent agreement for both atomization energies and geometries.

Time evolution of the electronic structure of 1T-TaS2 through the insulator-metal transition.

The photoemission spectra and the spectral function calculated by dynamical mean field theory show that this insulator-metal transition is driven solely by hot electrons.

Atomically thin MoS₂: a new direct-gap semiconductor.

The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,…,6 S-Mo-S monolayers have been investigated by optical spectroscopy and the effect of quantum confinement on the material's electronic structure is traced.