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Valleytronics of MoS2

This means the valley pseudospin and charge carrier spin degrees of freedom are coupled (spin-valley coupling). The spin and valley properties of charge carriers can be selected optically – through excitation polarisation (to choose the valley) and energy (to select the A or B exciton – and hence, the spin). When an in-plane electric field is applied, excitons may become disassociated, with the carriers retaining their valley and spin characteristics. Electrons (and holes) in opposing valleys will travel in opposite directions perpendicular to the field. This is called the 'Valley Hall effect' and could form the basis of future technologies, where more information can be encoded onto electrons because of these added degrees of freedom. a) σ+ circularly polarised light incident on a monolayer of MoS2 excites charge carriers in the K-valley (orange spheres). Light with energy degenerates with the A-exciton (red arrow) and excites spin-up electrons and spin-down holes. Conversely, light corresponding to the B-exciton (blue arrow) excites spin-down electrons and spin-up holes. An in-plane electric field causes electrons to accumulate on one edge of the layer and holes on the other. b) σ- light excites charge carriers in the K’-valley (green) with opposite spins to those in the K-valley, with the charges accumulating on opposite edges. c) Linearly polarised light with energy degenerates with the A-exciton excites charges in both valleys, with carriers carrying the same spins collecting on the same layer edge. d) A similar situation is realized following excitation with linearly polarised light degenerating with the B-exciton, with spins migrating to the opposite sides of the layer. Excitons in MoS2 have a valley lifetime (the time they remain in their original valley before scattering out) of a few picoseconds. In comparison, the valley lifetime of electrons is >100 nanoseconds, and holes may have an even longer lifetime. This represents the time to complete logic operations using the valley pseudospin and should be as large as possible for practical applications. If you are looking for high quality, high purity, and cost-effective Molybdenum disulfide, or if you require the latest price of Molybdenum disulfide, please feel free to email contact mis-asia.

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