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Spin effects in MoS 2 and WS 2 single layers
Author(s) -
Kioseoglou G.,
Korkusinski M.,
Scrace T.,
Hanbicki A. T.,
Currie M.,
Jonker B. T.,
Petrou A.,
Hawrylak P.
Publication year - 2016
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201510291
Subject(s) - trion , circular polarization , excited state , photoluminescence , electron , polarization (electrochemistry) , light emission , exciton , atomic physics , physics , magnetic field , condensed matter physics , materials science , optoelectronics , chemistry , quantum mechanics
Replacing the two sublattices of carbon atoms in graphene with transition metal atoms and chalcogenide dimers results in single layers of transition metal dichalcogenides (TMDCs). TMDCs are promising new materials for light and energy harvesting, transistors, sensors and quantum information processing. One way to access the distinctive functionality of these materials is via their optical selection rules. In particular, light with positive or negative helicity is absorbed differently, therefore, understanding the interaction of circularly polarized light with various TMDCs should enable future applications. Using the examples of MoS 2 and WS 2 we summarize some recent results that illustrate the potential of these materials. First, when optically excited with circularly polarized light, single layers of MoS 2 can emit light with an appreciable polarization. Depolarization mechanisms can be subsequently explored by monitoring the polarization of emitted photoluminescence as a function of the excess energy supplied to the system. As the energy of the pumping light increases further from the emission channel, the emission quickly becomes depolarized. The dominant relaxation mechanism is identified as phonon‐assisted intervalley scattering. In single layers of WS 2 containing electron gas, the main emission channel is from negatively charged excitons, or trions. In the presence of a two‐dimensional electron gas this trion emission is circularly polarized at zero magnetic field, even when excited with linearly polarized light. This spontaneous circular polarization of the trion has a linear dependence on magnetic field and can be attributed to the existence of a valley polarized state of the two‐dimensional electron gas. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)