Non-Hermitian theory of valley excitons in two-dimensional semiconductors
arXiv:2405.19007 · doi:10.1103/PhysRevLett.133.236902
Abstract
Electron-hole exchange interaction in two-dimensional transition metal dichalcogenides is extremely strong due to the dimension reduction, which promises valley-superposed excitonic states with linearly polarized optical emissions. However, strong circular polarization reflecting valley-polarized excitonic states is commonly observed in helicity-resolved optical experiments. Here we present a non-Hermitian theory of valley excitons by incorporating optical pumping and intrinsic decay, which unveils an anomalous valley-polarized excitonic state with elliptically polarized optical emission. This novel state arises from the non-Hermiticity induced parity-time ()-symmetry breaking, which impedes the experimental observation of intervalley excitonic coherence effect. At large excitonic center-of-mass momenta, the -symmetry is restored and the excitonic states recover their valley coherence. Interestingly, the linear polarization directions in optical emissions from these valley-superposed excitonic states are non-orthogonal and even become parallel at exceptional points. Our non-Hermitian theory also predicts a non-zero Berry curvature for valley excitons, which admits a topological excitonic Hall transport beyond the Hermitian predictions.
arXiv commentPublished in Phys. Rev. Lett. 133, 236902 (2024)
References in corpus (46)
- Real Spectra in Non-Hermitian Hamiltonians Having PT Symmetry
- Berry Phase Effects on Electronic Properties
- Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
- Control of valley polarization in monolayer MoS2 by optical helicity
- Valley polarization in MoS2 monolayers by optical pumping
- Making Sense of Non-Hermitian Hamiltonians
- MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
- Edge states and topological invariants of non-Hermitian systems
- Excitons in atomically thin transition metal dichalcogenides
- Exceptional Topology of Non-Hermitian Systems
- Non-Hermitian Physics
- Optical Generation of Excitonic Valley Coherence in Monolayer WSe2
- Topological phases of non-Hermitian systems
- The physics of exceptional points
- Symmetry and Topology in Non-Hermitian Physics
- Topological Band Theory for Non-Hermitian Hamiltonians
- Valley Dependent Optoelectronics from Inversion Symmetry Breaking
- BerkeleyGW: A Massively Parallel Computer Package for the Calculation of the Quasiparticle and Optical Properties of Materials and Nanostructures
- Exciton-polariton condensates
- Electronic structures and theoretical modelling of two-dimensional group-VIB transition metal dichalcogenides
- Excitonic linewidth approaching the homogeneous limit in MoS2 based van der Waals heterostructures : accessing spin-valley dynamics
- Berry phase effect in anomalous thermoelectric transport
- Intrinsic Exciton Linewidth in Monolayer Transition Metal Dichalcogenides
- Non-Hermitian Topology and Exceptional-Point Geometries
- Weyl Exceptional Rings in a Three-Dimensional Dissipative Cold Atomic Gas
- Topological acoustics
- Robust optical emission polarization in MoS2 monolayers through selective valley excitation
- Metrology with -symmetric cavities: Enhanced sensitivity near the -phase transition
- Observation of parity-time symmetry breaking in a single spin system
- Bulk-Boundary Correspondence in a Non-Hermitian System in One Dimension with Chiral-Inversion Symmetry
- Bright excitons in monolayer transition metal dichalcogenides: from Dirac cones to Dirac saddle points
- Advances and challenges in single-molecule electron transport
- Valley depolarization due to inter- and intra-valley electron-hole exchange interactions in monolayer MoS
- Valley excitons in two-dimensional semiconductors
- Exciton band structure of monolayer MoS2
- Direct Measurement of Exciton Valley Coherence in Monolayer WSe
- Exciton fine structure and spin decoherence in monolayers of transition metal dichalcogenides
- Topological Non-Hermitian skin effect
- Exciton diffusion and halo effects in monolayer semiconductors
- Nonanalyticity, Valley Quantum Phases, and Light-like Exciton Dispersion in Monolayer TMDs: Theory and First-Principles Calculations
- Anomalous light cones and valley optical selection rules of interlayer excitons in twisted heterobilayers
- The ultrafast onset of exciton formation in 2D semiconductors
- Bosonic condensation of exciton-polaritons in an atomically thin crystal
- Berry Phase Effect on Exciton Transport and Bose Einstein Condensate
- Double resonant Raman scattering and valley coherence generation in monolayer WSe2
- Berry connection induced anomalous wave-packet dynamics in non-Hermitian systems