Flipping exciton angular momentum with chiral phonons in MoSe${}_2$/WSe${}_2$ heterobilayers

Abstract

Identifying quantum numbers to label elementary excitations is essential for the correct description of light-matter interaction in solids. In monolayer semiconducting transition metal dichalcogenides (TMDs) such as MoSe${}_2$ or WSe${}_2$, most optoelectronic phenomena are described well by labelling electron and hole states with the spin projection along the normal to the layer (S${}_z$). In contrast, for WSe${}_2$/MoSe${}_2$ interfaces recent experiments show that taking S${}_z$ as quantum number is not a good approximation, and spin mixing needs to be always considered. Here we argue that the correct quantum number for these systems is not S${}_z$, but the $z$-component of the total angular momentum -- J${}_z$ = L${}_z$ + S${}_z$ -- associated to the C${}_3$ rotational lattice symmetry, which assumes half-integer values corresponding modulo 3 to distinct states. We validate this conclusion experimentally through the observation of strong intervalley scattering mediated by chiral optical phonons that -- despite carrying angular momentum 1 -- cause resonant intervalley transitions of excitons, with an angular momentum difference of 2.

arXiv commentare welcome

References in corpus (34)

• Excitons in atomically thin transition metal dichalcogenides
• Observation of Long-Lived Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructures
• Moiré Excitons in Van der Waals Heterostructures
• Signatures of moiré-trapped valley excitons in MoSe${}_2$/WSe${}_2$ heterobilayers
• Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
• 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
• Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
• Magnetic brightening and control of dark excitons in monolayer WSe2
• Valley contrasting chiral phonons in monolayer hexagonal lattices
• Long-lived direct and indirect interlayer excitons in van der Waals heterostructures
• In-plane Propagation of Light in Transition Metal Dichalcogenide Monolayers: Optical Selection Rules
• Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons
• Splitting between Bright and Dark excitons in Transition Metal Dichalcogenide Monolayers
• Magneto-Optics of Exciton Rydberg States in a Monolayer Semiconductor
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Transport Theory of Monolayer Transition-Metal Dichalcogenides through Symmetry
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Brightened spin-triplet interlayer excitons and optical selection rules in van der Waals heterobilayers
• Giant Zeeman splitting inducing near-unity valley polarization in van der Waals heterostructures
• Resonance effects in the Raman scattering of mono- and few layers MoSe${}_2$
• Entanglement of single-photons and chiral phonons in atomically thin WSe${}_2$
• Resolving spin, valley, and moiré quasi-angular momentum of interlayer excitons in WSe2/WS2 heterostructures
• Momentum-Dark Intervalley Exciton in Monolayer Tungsten Diselenide Brightened via Chiral Phonon
• Valley-selective chiral phonon replicas of dark excitons and trions in monolayer WSe2
• Discrete Interactions between a few Interlayer Excitons Trapped at a MoSe${}_2$-WSe${}_2$ Heterointerface
• Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure
• Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems
• Signature of electronic excitations in the Raman spectrum of graphene
• Electronic excitations and electron-phonon coupling in bulk graphite through Raman scattering in high magnetic fields
• Semiconducting van der Waals Interfaces as Artificial Semiconductors
• Circular dichroism of magneto-phonon resonance in doped graphene

Cited by in corpus (18)

• Quantum Nanophotonics in Two-Dimensional Materials
• Moiré excitons in MoSe${}_2$-WSe${}_2$ heterobilayers and heterotrilayers
• Moiré-trapped interlayer trions in a charge-tunable WSe${}_2$/MoSe${}_2$ heterobilayer
• Magnetooptics of layered two-dimensional semiconductors and heterostructures: progress and prospects
• Electrically controlled emission from singlet and triplet exciton species in atomically thin light emitting diodes
• Optical read-out of Coulomb staircases in a moiré superlattice via trapped interlayer trions
• Rydberg series of dark excitons and the conduction band spin-orbit splitting in monolayer WSe${}_2$
• Chiral Phonons in Moiré Superlattices
• Chiral valley phonons and flat phonon bands in moiré materials
• Interlayer exciton valley polarization dynamics in large magnetic fields
• Signatures of electric field and layer separation effects on the spin-valley physics of MoSe${}_2$/WSe${}_2$ heterobilayers: from energy bands to dipolar excitons
• Lattice reconstruction in MoSe${}_2$-WSe${}_2$ heterobilayers synthesized by chemical vapor deposition
• Exciton-activated effective phonon magnetic moment in monolayer MoS2
• Interlayer excitonic spectra of vertically stacked MoSe${}_2$/WSe${}_2$ heterobilayers
• Electric field control of phonon angular momentum in perovskite BaTiO${}_3$
• Chiral phonons in binary compounds $A$Bi ($A$ = K, Rb, Cs) with P2${}_1$/c structure
• Physics of Phonons in Systems with Approximate Screw Symmetry
• Chiral phonon in the cubic system based on the Laves phase of $A$Bi${}_2$ ($A=$K, Rb, Cs)