Ultrafast Hidden Spin Polarization Dynamics of Bright and Dark Excitons in 2H-WSe${}_2$

Abstract

We performed spin-, time- and angle-resolved extreme ultraviolet photoemission spectroscopy (STARPES) of excitons prepared by photoexcitation of inversion-symmetric 2H-WSe${}_2$ with circularly polarized light. The very short probing depth of XUV photoemission permits selective measurement of photoelectrons originating from the top-most WSe${}_2$ layer, allowing for direct measurement of hidden spin polarization of bright and momentum-forbidden dark excitons. Our results reveal efficient chiroptical control of bright excitons' hidden spin polarization. Following optical photoexcitation, intervalley scattering between nonequivalent K-K' valleys leads to a decay of bright excitons' hidden spin polarization. Conversely, the ultrafast formation of momentum-forbidden dark excitons acts as a local spin polarization reservoir, which could be used for spin injection in van der Waals heterostructures involving multilayer transition metal dichalcogenides.

References in corpus (28)

• 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
• Van der Waals heterostructures for spintronics and opto-spintronics
• Hidden spin polarization in inversion-symmetric bulk crystals
• Excitonic linewidth and coherence lifetime in monolayer transition metal dichalcogenides
• Direct observation of spin-polarised bulk bands in an inversion-symmetric semiconductor
• Directly visualizing the momentum forbidden dark excitons and their dynamics in atomically thin semiconductors
• Electronic properties of single-layer and multilayer transition metal dichalcogenides $M{X}_2$ ($M=$ Mo, W and $X=$ S, Se)
• Generation and evolution of spin-, valley- and layer-polarized excited carriers in inversion-symmetric WSe2
• Spin-flip processes and ultrafast magnetization dynamics in Co - unifying the microscopic and macroscopic view of femtosecond magnetism
• Local Berry curvature signatures in dichroic angle-resolved photoelectron spectroscopy
• The role of momentum-dark excitons in the elementary optical response of bilayer WSe${}_2$
• Selective probing of hidden spin-polarized states in inversion-symmetric bulk MoS2
• Experimental observation of hidden Berry curvature in inversion-symmetric bulk 2H-WSe2
• Unconventional superconductivity in bilayer transition metal dichalcogenides
• Direct measurement of key exciton properties: energy, dynamics and spatial distribution of the wave function
• Spin-Polarized Surface Resonances Accompanying Topological Surface State Formation
• Revealing Hidden Orbital Pseudospin Texture with Time-Reversal Dichroism in Photoelectron Angular Distributions
• Ultrafast spin polarization control of Dirac fermions in topological insulators
• Momentum resolved spin dynamics of bulk and surface excited states in the topological insulator $\mathrm{B}{\mathrm{i}}_2\mathrm{S}{\mathrm{e}}_3$
• Intrinsic circular polarization in centrosymmetric stacks of transition-metal dichalcogenides
• A quantitative comparison of time-of-flight momentum microscopes and hemispherical analyzers for time- and angle-resolved photoemission spectroscopy experiments
• Spin- and angle-resolved photoemission on topological materials
• Spin-, time- and angle-resolved photoemission spectroscopy on WTe${}_2$
• Spin accumulation and dynamics in inversion-symmetric van der Waals crystals
• Layer and orbital interference effects in photoemission from transition metal dichalcogenides
• Distinctive Picosecond Spin Polarization Dynamics in Bulk Half-Metals

Cited by in corpus (3)

• Berry Curvature Signatures in Chiroptical Excitonic Transitions
• Transition from Optically Excited to Intrinsic Spin Polarization in WSe${}_2$
• Light-matter interactions in layered materials and heterostructures: from moiré physics and magneto-optical effects to ultrafast dynamics and hybrid meta-photonics