Valley dynamics of excitons in monolayer dichalcogenides. Issue 7 (20th June 2017)

• Record Type: Journal Article
• Authors: Plechinger, Gerd; Nagler, Philipp; Arora, Ashish; Schmidt, Robert; Chernikov, Alexey; Lupton, John; Bratschitsch, Rudolf; Schüller, Christian; Korn, Tobias
• Is Part Of: Physica status solidi. Volume 11:Issue 7(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-06-20
• Subjects: excitons -- transition metal dichalcogenides -- two‐dimensional materials -- valley dynamics -- valleytronics; Solid state physics -- Periodicals; 530.4105
• DOI: 10.1002/pssr.201700131
• Languages: English
• ISSNs: 1862-6254

Abstract

Abstract : Monolayer transition‐metal dichalcogenides (TMDCs) have recently emerged as possible candidates for valleytronic applications, as the spin and valley pseudospin are directly coupled and stabilized by a large spin splitting. In these semiconducting materials, optically excited electron–hole pairs form tightly Coulomb‐bound excitons with large binding energies. The selection rules for excitonic transitions allow for direct optical generation of a valley‐polarized exciton population using resonant excitation. Here, we investigate the exciton valley dynamics in monolayers of three different TMDCs by means of time‐resolved Kerr rotation at low temperatures. We observe pronounced differences in the valley dynamics of tungsten‐ and molybdenum‐based TMDCs, which are directly related to the opposite order of the conduction‐band spin splitting in these materials. Abstract : Monolayer transition‐metal dichalcogenides (TMDCs) are characterized by tightly bound excitons and a peculiar band structure with spin–valley coupling. Tungsten‐ and molybdenum‐based TMDC monolayers have opposite spin splitting of the conduction bands. In this Letter, Plechinger et al. investigate exciton valley dynamics in WS2, WSe2 and MoS2 monolayers, and observe the pronounced influence of the different spin splitting in these materials on valley physics.