Larger than 80% Valley Polarization of Free Carriers in Singly-Oriented Single Layer WS${}_2$ on Au(111)

Abstract

We employ time- and angle-resolved photoemission spectroscopy to study the spin- and valley-selective photoexcitation and dynamics of free carriers at the K and K' points in singly-oriented single layer WS${}_2$/Au(111). Our results reveal that in the valence band maximum an ultimate valley polarization of free holes of 84% can be achieved upon excitation with circularly polarized light at room temperature. Notably, we observe a significantly smaller valley polarization for the photoexcited free electrons in the conduction band minimum. Clear differences in the carrier dynamics between electrons and holes imply intervalley scattering processes into dark states being responsible for the efficient depolarization of the excited electron population.

arXiv comment13 pages, 7 figures

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Cited by in corpus (13)

• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• Lightwave-controlled band engineering in quantum materials
• Nonequilibrium Lattice Dynamics in Monolayer MoS2
• Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS${}_2$
• Direct view of phonon dynamics in atomically thin MoS${}_2$
• Two-dimensional plasmonic polarons in n-doped monolayer MoS2
• Accessing the spectral function of in operando devices by angle-resolved photoemission spectroscopy
• Chirality of Valley Excitons in Monolayer Transition-Metal Dichalcogenides
• Vibrational dichroism of chiral valley phonons
• Layer and orbital interference effects in photoemission from transition metal dichalcogenides
• Momentum-resolved linear dichroism in bilayer MoS${}_2$
• Phase engineering in tantalum sulfide monolayers on Au(111)
• Ultrafast Phonon-Diffuse Scattering as a Tool for Observing Chiral Phonons in Monolayer Hexagonal Lattices