Abstract
The control of the valley degree of freedom lies at the core of interest in monolayer transition metal dichalcogenides, where specific valley-spin excitation can be created using circularly polarized light. Measurement and manipulation of the valley index has also been achieved, but mainly with purely optical methods. Here, in monolayer , we identify a response to the valley polarization of excitons in the longitudinal electrical transport when the valley degeneracy is broken by an out-of-plane magnetic field . The spin information is also simultaneously determined with spin-sensitive contacts. In the presence of , a significant modulation of the photocurrent is observed as a function of the circular polarization state of the excitation. We attribute this effect to unbalanced transport of valley-polarized trions induced by the opposite Zeeman shifts of two ( and ) valleys. Our interpretation is supported by the contrasting behavior in bilayer , as well as the observed doping and spatial dependence of the valley photocurrent.
- Received 12 August 2018
- Revised 24 December 2018
DOI:https://doi.org/10.1103/PhysRevLett.122.127401
© 2019 American Physical Society