Spin and Valley Control of Free Carriers in Single-Layer WS${}_2$

Abstract

The semiconducting single-layer transition metal dichalcogenides have been identified as ideal materials for accessing and manipulating spin- and valley-quantum numbers due to a set of favorable optical selection rules in these materials. Here, we apply time- and angle-resolved photoemission spectroscopy to directly probe optically excited free carriers in the electronic band structure of a high quality single layer of WS${}_2$. We observe that the optically generated free hole density in a single valley can be increased by a factor of 2 using a circularly polarized optical excitation. Moreover, we find that by varying the photon energy of the excitation we can tune the free carrier density in a given spin-split state around the valence band maximum of the material. The control of the photon energy and polarization of the excitation thus permits us to selectively excite free electron-hole pairs with a given spin and within a single valley.

5 pages, 4 figures

References in corpus (5)

• Valley polarization in MoS2 monolayers by optical pumping
• The Valley Hall Effect in MoS2 Transistors
• Valley filter and valley valve in graphene
• Computational 2D Materials Database: Electronic Structure of Transition-Metal Dichalcogenides and Oxides
• Generation and Electric Control of Spin-Coupled Valley Current in WSe2

Cited by in corpus (15)

• Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors
• Direct Determination of Band Gap Renormalization in Photo-Excited Monolayer MoS2
• Time- and Angle-Resolved Photoemission Studies of Quantum Materials
• In-situ exfoliation method of large-area 2D materials
• Contact-Induced Semiconductor-to-Metal Transition in Single-Layer WS${}_2$
• Momentum-Resolved Exciton Coupling and Valley Polarization Dynamics in Monolayer WS${}_2$
• Advancing time- and angle-resolved photoemission spectroscopy: The role of ultrafast laser development
• Layer and orbital interference effects in photoemission from transition metal dichalcogenides
• Revealing Ultrafast Phonon Mediated Inter-Valley Scattering through Transient Absorption and High Harmonic Spectroscopies
• Momentum-resolved linear dichroism in bilayer MoS${}_2$
• Adsorption and dissociation of diatomic molecules in monolayer $1H$-MoSe${}_2$
• Infrared study of the pressure-induced isostructural metallic transition in Mo${}_{0:5}$W${}_{0:5}$S${}_2$
• Phase engineering in tantalum sulfide monolayers on Au(111)
• Ultrafast Phonon-Diffuse Scattering as a Tool for Observing Chiral Phonons in Monolayer Hexagonal Lattices
• Symmetry-breaking and spin-blockage effects on carrier dynamics in single-layer tungsten diselenide