期刊
PHYSICAL REVIEW LETTERS
卷 123, 期 23, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.123.236802
关键词
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资金
- German Research Foundation [BA 2177/10-1]
- VILLUM FONDEN through the Centre of Excellence for Dirac Materials [11744]
- Danish Council for Independent Research, Natural Sciences under the Sapere Aude program [DFF-4002-00029]
We employ time- and angle-resolved photoemission spectroscopy to study the spin- and valley-selective photoexcitation and dynamics of free carriers at the (K) over bar and (K') over bar 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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