Spin/valley pumping of resident electrons in WSe<sub>2</sub> and WS<sub>2</sub> monolayers.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34526493.
- Also identified by DOI 10.1038/s41467-021-25747-5 and PMC identifier 8443707.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Monolayers of transition metal dichalcogenides are ideal materials to control both spin and valley degrees of freedom either electrically or optically. Nevertheless, optical excitation mostly generates excitons species with inherently short lifetime and spin/valley relaxation time. Here we demonstrate a very efficient spin/valley optical pumping of resident electrons in n-doped WSe<sub>2</sub> and WS<sub>2</sub> monolayers. We observe that, using a continuous wave laser and appropriate doping and excitation densities, negative trion doublet lines exhibit circular polarization of opposite sign and the photoluminescence intensity of the triplet trion is more than four times larger with circular excitation than with linear excitation. We interpret our results as a consequence of a large dynamic polarization of resident electrons using circular light.