Optical detection of long electron spin transport lengths in a monolayer semiconductor

Abstract

Using a spatially-resolved optical pump-probe experiment, we measure the lateral transport of spin/valley polarized electrons over very long distances (tens of micrometers) in a single WSe2 monolayer. By locally pumping the Fermi sea of 2D electrons to a high degree of spin/valley polarization (up to 75%) using circularly-polarized light, the lateral diffusion of the electron polarization can be mapped out via the photoluminescence induced by a spatially-separated and linearly-polarized probe laser. Up to 25% spin-valley polarization is observed at pump-probe separations up to 20 microns. Characteristic spin/valley diffusion lengths of 18 +/- 3 um are revealed at low temperatures. The dependence on temperature, pump helicity, pump intensity, and electron density highlight the key roles played by spin relaxation time and pumping efficiency on polarized electron transport in monolayer semiconductors possessing spin-valley locking.

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Cited by in corpus (6)

• Electrically Controlled Interfacial Charge Transfer Induced Excitons in MoSe2-WSe2 Lateral Heterostructure
• Long-distance decay-less spin transport in indirect excitons in a van der Waals heterostructure
• Two dimensional semiconductors: optical and electronic properties
• Spin relaxation of localized electrons in monolayer MoSe${}_2$: importance of random effective magnetic fields
• Nonthermal electron-photon steady states in open cavity quantum materials
• Exchange-enhanced spin-orbit splitting and its density dependence for electrons in monolayer transition metal dichalcogenides