80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111)

H Beyer, G Rohde, Antonija Grubišić Čabo, A Stange, T Jacobsen, Luca Bignardi, D Lizzit, Paolo Lacovig, Charlotte E. Sanders, Silvano Lizzit, K Rossnagel, Philip Hofmann, M Bauer

Research output: Contribution to journalArticleResearchpeer-review

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 WS2/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.
Original languageEnglish
Number of pages6
JournalPhysical Review Letters
Volume123
Issue number23
DOIs
Publication statusPublished - 4 Dec 2019
Externally publishedYes

Cite this

Beyer, H., Rohde, G., Grubišić Čabo, A., Stange, A., Jacobsen, T., Bignardi, L., ... Bauer, M. (2019). 80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111). Physical Review Letters, 123(23). https://doi.org/10.1103/PhysRevLett.123.236802
Beyer, H ; Rohde, G ; Grubišić Čabo, Antonija ; Stange, A ; Jacobsen, T ; Bignardi, Luca ; Lizzit, D ; Lacovig, Paolo ; Sanders, Charlotte E. ; Lizzit, Silvano ; Rossnagel, K ; Hofmann, Philip ; Bauer, M. / 80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111). In: Physical Review Letters. 2019 ; Vol. 123, No. 23.
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title = "80{\%} Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 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 WS2/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.",
author = "H Beyer and G Rohde and {Grubišić Čabo}, Antonija and A Stange and T Jacobsen and Luca Bignardi and D Lizzit and Paolo Lacovig and Sanders, {Charlotte E.} and Silvano Lizzit and K Rossnagel and Philip Hofmann and M Bauer",
year = "2019",
month = "12",
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doi = "10.1103/PhysRevLett.123.236802",
language = "English",
volume = "123",
journal = "Physical Review Letters",
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Beyer, H, Rohde, G, Grubišić Čabo, A, Stange, A, Jacobsen, T, Bignardi, L, Lizzit, D, Lacovig, P, Sanders, CE, Lizzit, S, Rossnagel, K, Hofmann, P & Bauer, M 2019, '80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111)', Physical Review Letters, vol. 123, no. 23. https://doi.org/10.1103/PhysRevLett.123.236802

80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111). / Beyer, H; Rohde, G; Grubišić Čabo, Antonija; Stange, A; Jacobsen, T; Bignardi, Luca; Lizzit, D; Lacovig, Paolo; Sanders, Charlotte E.; Lizzit, Silvano; Rossnagel, K; Hofmann, Philip; Bauer, M.

In: Physical Review Letters, Vol. 123, No. 23, 04.12.2019.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - 80% Valley Polarization of Free Carriers in Singly Oriented Single-Layer WS2 on Au(111)

AU - Beyer, H

AU - Rohde, G

AU - Grubišić Čabo, Antonija

AU - Stange, A

AU - Jacobsen, T

AU - Bignardi, Luca

AU - Lizzit, D

AU - Lacovig, Paolo

AU - Sanders, Charlotte E.

AU - Lizzit, Silvano

AU - Rossnagel, K

AU - Hofmann, Philip

AU - Bauer, M

PY - 2019/12/4

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N2 - 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 WS2/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.

AB - 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 WS2/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.

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DO - 10.1103/PhysRevLett.123.236802

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JO - Physical Review Letters

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