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Scrace T, Tsai Y, Barman B, Schweidenback L, Petrou A, Kioseoglou G, Ozfidan I, Korkusinski M, Hawrylak P. Magnetoluminescence and valley polarized state of a two-dimensional electron gas in WS2 monolayers. Nat Nanotechnol 2015; 10:603-7. [PMID: 25961511 DOI: 10.1038/nnano.2015.78] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 03/16/2015] [Indexed: 05/09/2023]
Abstract
Materials often exhibit fundamentally new phenomena in reduced dimensions that potentially lead to novel applications. This is true for single-layer, two-dimensional semiconductor crystals of transition-metal dichalcogenides, MX2 (M = Mo, W and X = S, Se). They exhibit direct bandgaps with energies in the visible region at the two non-equivalent valleys in the Brillouin zone. This makes them suitable for optoelectronic applications that range from light-emitting diodes to light harvesting and light sensors, and to valleytronics. Here, we report the results of a magnetoluminescence study of WS2 single-layer crystals in which the strong spin-orbit interaction additionally locks the valley and spin degrees of freedom. The recombination of the negatively charged exciton in the presence of a two-dimensional electron gas (2DEG) is found to be circularly polarized at zero magnetic field despite being excited with unpolarized light, which indicates that the existence of a valley polarized 2DEG is caused by valley and spin locking and strong electron-electron interactions.
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Affiliation(s)
- T Scrace
- University at Buffalo, SUNY, Buffalo, New York 14260, USA
| | - Y Tsai
- University at Buffalo, SUNY, Buffalo, New York 14260, USA
| | - B Barman
- University at Buffalo, SUNY, Buffalo, New York 14260, USA
| | | | - A Petrou
- University at Buffalo, SUNY, Buffalo, New York 14260, USA
| | | | - I Ozfidan
- 1] Quantum Theory Group, Emerging Technologies Division, National Research Council, Ottawa K1A 0R6, Ontario, Canada [2] Department of Physics, University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - M Korkusinski
- Quantum Theory Group, Emerging Technologies Division, National Research Council, Ottawa K1A 0R6, Ontario, Canada
| | - P Hawrylak
- 1] Quantum Theory Group, Emerging Technologies Division, National Research Council, Ottawa K1A 0R6, Ontario, Canada [2] Department of Physics, University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
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