Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points

Abstract

In monolayer transition metal dichalcogenides, tightly bound excitons have been discovered with a valley pseudospin that can be optically addressed through polarization selection rules. Here, we show that this valley pseudospin is strongly coupled to the exciton center-of-mass motion through electron-hole exchange. This coupling realizes a massless Dirac cone with chirality index I=2 for excitons inside the light cone, i.e. bright excitons. Under moderate strain, the I=2 Dirac cone splits into two degenerate I=1 Dirac cones, and saddle points with a linear Dirac spectrum emerge in the bright exciton dispersion. Interestingly, after binding an extra electron, the charged exciton becomes a massive Dirac particle associated with a large valley Hall effect protected from intervalley scattering. Our results point to unique opportunities to study Dirac physics, with exciton's optical addressability at specifiable momentum, energy and pseudospin. The strain-tunable valley-orbit coupling also implies new structures of exciton condensates, new functionalities of excitonic circuits, and possibilities for mechanical control of valley pseudospin.

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Cited by in corpus (174)

• Two-Dimensional Material Nanophotonics
• Observation of Moiré Excitons in WSe2/WS2 Heterostructure Superlattices
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides
• Fermi polaron-polaritons in charge-tunable atomically thin semiconductors
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Valley dynamics probed through charged and neutral exciton emission in monolayer WSe2
• Topological Exciton Bands in Moiré Heterojunctions
• Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons
• Two-dimensional semiconductors in the regime of strong light-matter coupling
• Valley excitons in two-dimensional semiconductors
• Exciton band structure of monolayer MoS2
• Charged excitons in monolayer WSe${}_2$: experiment and theory
• Direct Measurement of Exciton Valley Coherence in Monolayer WSe${}_2$
• Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers
• Nonanalyticity, Valley Quantum Phases, and Light-like Exciton Dispersion in Monolayer TMDs: Theory and First-Principles Calculations
• WSe2 light-emitting tunneling transistors with enhanced brightness at room temperature
• Ultrafast Manipulation of Valley Pseudospin
• One-Dimensional Moiré Excitons in Transition-Metal Dichalcogenide Heterobilayers
• Anomalous light cones and valley optical selection rules of interlayer excitons in twisted heterobilayers
• Optical properties of atomically thin transition metal dichalcogenides: Observations and puzzles
• Observation of Wigner crystal of electrons in a monolayer semiconductor
• Dark excitons in transition metal dichalcogenides
• Radiative Lifetimes of Excitons and Trions in Monolayers of Metal Dichalcogenide MoS2
• Exciton Dynamics in Monolayer Transition Metal Dichalcogenides
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Control of Exciton Valley Coherence in Transition Metal Dichalcogenide Monolayers
• Defect-induced modification of low-lying excitons and valley selectivity in monolayer transition metal dichalcogenides
• Polarization analysis of excitons in monolayer and bilayer transition-metal dichalcogenides
• Valley Polarization by Spin Injection in a Light-Emitting van der Waals Heterojunction
• Emerging Photoluminescence from the Dark-Exciton Phonon Replica in Monolayer WSe2
• Realization of an atomically thin mirror using monolayer MoSe2
• Exciton band structure in two-dimensional materials
• Magneto-optics in transition metal diselenide monolayers
• Biexciton fine structure in monolayer transition metal dichalcogenides
• Probing the spin-polarized electronic band structure in monolayer transition metal dichalcogenides by optical spectroscopy
• Excitonic valley effects in monolayer WS${}_2$ under high magnetic fields
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
• Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2
• Temperature Dependent Valley Relaxation Dynamics in Single Layer WS2 Measured Using Ultrafast Spectroscopy
• Optical properties of charged excitons in two-dimensional semiconductors
• Momentum-Dark Intervalley Exciton in Monolayer Tungsten Diselenide Brightened via Chiral Phonon
• Chiral plasmons without magnetic field
• Interplay between spin proximity effect and charge-dependent exciton dynamics in MoSe${}_2$ / CrBr${}_3$ van der Waals heterostructures
• Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Spin-flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers
• Valley coherent exciton-polaritons in a monolayer semiconductor
• Direct Observation of Gate Tunable Dark Trions in Monolayer WSe2
• Highly Valley-Polarized Singlet and Triplet Interlayer Excitons in van der Waals Heterostructure
• Multipath optical recombination of intervalley dark excitons and trions in monolayer WSe${}_2$
• Exciton-Scattering-Induced Dephasing in Two-Dimensional Semiconductors
• Singlet and triplet trions in WS${}_2$ monolayer encapsulated in hexagonal boron nitride
• The valley Zeeman effect in inter- and intra-valley trions in monolayer WSe${}_2$
• Chiral excitonic order from twofold van Hove singularities in kagome metals
• Intrinsic exciton states mixing and non-linear optical properties in transition metal dichalcogenide monolayers
• Magneto-photoluminescence of exciton Rydberg states in monolayer WSe${}_2$
• Optical signatures of charge order in a Mott-Wigner state
• Marrying excitons and plasmons in monolayer transition-metal dichalcogenides
• Many-Body Simulation of Two-Dimensional Electronic Spectroscopy of Excitons and Trions in Monolayer Transition-Metal Dichalcogenides
• Microscopic Origin of the Valley Hall Effect in Transition Metal Dichalcogenides Revealed by Wavelength Dependent Mapping
• Opportunities in Electrically Tunable 2D Materials Beyond Graphene: Recent Progress and Future Outlook
• Optical control of a single spin-valley in charged WSe${}_2$ quantum dots
• Inter-valley dark trion states with spin lifetimes of 150 ns in WSe${}_2$
• Probing exciton dispersions of freestanding monolayer WSe2 by momentum resolved electron energy loss spectroscopy
• Distinctive signatures of the spin- and momentum-forbidden dark exciton states in the photo-luminescences of strained WSe${}_2$ monolayers under thermalization
• Novel valley depolarization dynamics and valley Hall effect of exciton in mono- and bilayer MoS${}_2$
• Superior valley polarization and coherence of 2s excitons in monolayer WSe2
• Interface excitons at lateral heterojunctions in monolayer semiconductors
• Many-body effects in nonlinear optical responses of 2D layered semiconductors
• Theory of intervalley Coulomb interactions in monolayer transition-metal dichalcogenides
• Hybrid k$\cdot$p tight-binding model for subbands and infrared intersubband optics in few-layer films of transition-metal dichalcogenides: MoS${}_2$, MoSe${}_2$, WS${}_2$ and WSe${}_2$
• Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS${}_2$
• Exciton valley depolarization in monolayer transition-metal dichalcogenides
• Trion induced photoluminescence of a doped MoS2 monolayer
• Near-field relaxation of a quantum emitter to 2D semiconductors: surface dissipation and exciton polaritons
• Exciton-polaritons in transition-metal dichalcogenides and their direct excitation via energy transfer
• Optical Valley Hall Effect based on Transitional Metal Dichalcogenide cavity polaritons
• Atomically thin semiconductors as nonlinear mirrors
• Interfacial bound exciton state in a hybrid structure of monolayer WS2 and InGaN quantum dots
• Enhancement of Exciton Valley Polarization in Monolayer MoS2 Induced by Scattering
• Exciton-phonon relaxation bottleneck and radiative decay of thermal exciton reservoir in two-dimensional materials
• Exciton fine structure splitting and linearly polarized emission in strained transition-metal dichalcogenide monolayers
• Optical fingerprint of dark 2p-states in transition metal dichalcogenides
• Valley Degree of Freedom in Two-Dimensional van der Waals Materials
• Strain control of exciton and trion spin-valley dynamics in monolayer transition metal dichalcogenides
• Band nesting and exciton spectrum in monolayer MoS${}_2$
• Influence of Defects on the Valley Polarization Properties of Monolayer MoS${}_2$ Grown by Chemical Vapor Deposition
• Observation of ~100% valley-coherent excitons in monolayer MoS2 through giant enhancement of valley coherence time
• Skew Scattering and Side Jump Drive Exciton Valley Hall Effect in Two-Dimensional Crystals
• Excitonic Complexes and Emerging Interlayer Electron-Phonon Coupling in BN Encapsulated Monolayer Semiconductor Alloy: WS0.6Se1.4
• Charged exctions in two-dimensional transition-metal dichalcogenides - semiclassical calculation of Berry-curvature effects
• Rashba spin-orbit coupling, strong interactions, and the BCS-BEC crossover in the ground state of the two-dimensional Fermi Gas
• Electric Dipole Spin Resonance of 2D Semiconductor Spin Qubits
• Mott-moiré excitons
• Observation of Ultralong Valley Lifetime in WSe2/MoS2 Heterostructures
• Control of the exciton valley dynamics in van der Waals heterostructures
• Resonantly excited exciton dynamics in two-dimensional MoSe${}_2$ monolayers
• Trions in MoS${}_2$ are quantum superpositions of intra- and intervalley spin states
• Trion photoluminescence and trion stability in atomically thin semiconductors
• Polariton Hall Effect in Transition-Metal Dichalcogenides
• Long-lived Topological Flatband Excitons in Semiconductor Moiré Heterostructures: a Bosonic Kane-Mele Model Platform
• Probing biexciton in monolayer WS${}_2$ through controlled many-body interaction
• The strong modulation limit of excitons and trions in moiré materials
• Chiral topological excitons in the monolayer transition metal dichalcogenides
• Keldysh field theory of dynamical exciton condensation transitions in nonequilibrium electron-hole bilayers
• Dynamical exciton condensates in biased electron-hole bilayers
• Chiral Topological Excitons in a Chern Band Insulator
• Chiral excitonics in monolayer semiconductors on patterned dielectric
• Intrinsic circularly-polarized exciton emission in a twisted van-der-Waals heterostructure
• Intervalley electron-hole exchange interaction and impurity-assisted recombination of indirect excitons in WS${}_2$ and WSe${}_2$ monolayers
• Quadrupolar Excitons in MoSe${}_2$ Bilayers
• Interlayer excitonic spectra of vertically stacked MoSe${}_2$/WSe${}_2$ heterobilayers
• Optical signatures of periodic magnetization: the moiré Zeeman effect
• $\Gamma$-valley assisted intervalley scattering on monolayer and bilayer WS2 revealed by time-resolved Kerr rotation spectroscopy
• Anisotropic exciton transport in transition-metal dichalcogenides
• Rotons in Optical Excitation Spectra of Monolayer Semiconductors
• Nonlinear spectroscopy of excitonic states in transition metal dichalcogenides
• Optical fingerprint of non-covalently functionalized transition metal dichalcogenides
• Electrically tunable layer-hybridized trions in doped WSe${}_2$ bilayers
• Intrinsic edge excitons in two-dimensional MoS${}_2$
• Effect of intravalley and intervalley electron-hole exchange on the nonlinear optical response of monolayer MoSe${}_2$
• Valley-contrasting interband transitions and excitons in symmetrically biased dice model
• Excitonic insulator phase and dynamics of condensate in a topological one-dimensional model
• Inheritance of the exciton geometric structure from Bloch electrons in two-dimensional layered semiconductors
• Electromagnetic field assisted exciton diffusion in moiré superlattices
• Valley-mediated singlet- and triplet-polaron interactions and quantum dynamics in a doped WSe${}_2$ monolayer
• Diffusive real-time dynamics of a particle with Berry curvatures
• Coherent spin dynamics of excitons in strained monolayer semiconductors
• Longitudinal-transverse splitting and fine structure of Fermi polarons in two-dimensional semiconductors
• Searching for Unconventional Superfluid in Excitons of Monolayer Semiconductors
• Cross-dimensional valley excitons from Förster coupling in arbitrarily twisted stacks of monolayer semiconductors
• Two dimensional semiconductors: optical and electronic properties
• Dynamic Valley Polarization in Moire Quantum Dots
• Local Sensing of Correlated Electrons in Dual-moiré Heterostructures using Dipolar Excitons
• Waveguiding valley excitons in monolayer transition metal dicalcogenides by dielectric interfaces in the substrate
• Excitons and trions in CrSBr bilayers
• Strong Cavity-Pseudospin Coupling in Monolayer Transition Metal Dichalcogenides: Spontaneous Spin-Oscillations and Magnetometry
• Magneto-Optical Measurements of the Negatively Charged 2$s$ Exciton in WSe${}_2$
• Laser-field detuning assisted optimization of exciton valley dynamics in monolayer WSe${}_2$: Geometric quantum speed limit
• Brightening odd-parity excitons in transition-metal dichalcogenides: Rashba spin-orbit interaction, skyrmions, and cavity polaritons
• Förster valley-orbit coupling and topological lattice of hybrid moiré excitons
• Twistronics and moiré superlattice physics in 2D transition metal dichalcogenides
• Single photon emitters with polarization and orbital angular momentum locking in monolayer semiconductors
• Hybrid dark excitons in monolayer ${MoS}_2$
• Non-Hermitian theory of valley excitons in two-dimensional semiconductors
• Electrostatic control of the trion fine structure in transition metal dichalcogenide monolayers
• Fundamental limits for non-destructive measurement of a single spin by Faraday rotation
• Energy shifts and broadening of excitonic resonances in electrostatically-doped semiconductors
• Optically and magnetically addressable valley pseudospin of interlayer excitons in bilayer MoS2
• Motion of 2D exciton in momentum space leads to pseudospin distribution narrowing on the Bloch Sphere
• Optical injection of a spin current into a zigzag nanoribbon of monolayer MoS2 with antiferromagnetic Kekule distortion
• Valley polarization fluctuations, bistability, and switching in two-dimensional semiconductors
• Chiral excitonic systems in twisted bilayers from Förster coupling and unconventional excitonic Hall effects
• Dimensionality-Dependent Exciton Dispersion in a Single-Band Mott Insulator
• Signatures of valley drift in the diversified band dispersions of bright, gray, and dark excitons in MoS2 monolayers under uni-axial strains
• Helicoidal excitonic phase in an electron-hole double layer system
• Engineering the Radiative Dynamics of Thermalized Excitons with Metal Interfaces
• Polarized and narrow excitonic emission from graphene-capped monolayer WS${}_2$ through resonant phonon relaxation
• Engineering topological exciton structures in two-dimensional semiconductors by a periodic electrostatic potential
• Dirac's spectrum from Newton laws in graphene
• Multistable excitonic Stark effect
• Twisted-light-revealed Lightlike Exciton Dispersion in Monolayer MoS2
• Enhanced interlayer electron transfer by surface treatments in mixed-dimensional van der Waals semiconductor heterostructures
• Valley lifetimes of conduction band electrons in monolayer WSe${}_2$
• Single Quantum Emitters in Monolayer Semiconductors
• Trion-phonon interaction in atomically thin semiconductors
• Optical Measurement of Pseudo-Spin Texture of the Exciton Fine-Structure in Monolayer WSe2 within the Light Cone
• Room temperature nanocavity laser with interlayer excitons in 2D heterostructures
• Room temperature interlayer exciton valley polarization and valley Hall effect
• Non-local interactions and supersolidity of moiré excitons
• Valley-controlled many-body exciton interactions in monolayer WSe${}_2$ phototransistors