Spin–flip processes and radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers. (12th August 2016)

• Record Type: Journal Article
• Authors: Slobodeniuk, A O; Basko, D M
• Is Part Of: 2D materials. Volume 3:Number 3(2016)
• Publication Date: 2016-08-12
• Subjects: transition metal dichalcogenide monolayers -- electronic and optical properties -- decay rate of dark excitons; 71.35.-y -- 78.67.-n -- 72.25.Rb; Graphene -- Periodicals; Materials science -- Periodicals; Nanostructured materials -- Periodicals; 620.115
• DOI: 10.1088/2053-1583/3/3/035009
• Languages: English
• ISSNs: 2053-1583

Abstract

Abstract: We perform a theoretical study of radiative decay of dark intravalley excitons in transition metal dichalcogenide monolayers. This decay necessarily involves an electronic spin flip. The intrinsic decay mechanism due to interband spin–flip dipole moment perpendicular to the monolayer plane, gives a rate about 100–1000 times smaller than that of bright excitons. However, we find that this mechanism also introduces an energy splitting due to a local field effect, and the whole oscillator strength is contained in the higher-energy component, while the lowest-energy state remains dark and needs an extrinsic spin–flip mechanism for the decay. Rashba effect due to a perpendicular electric field or a dielectric substrate, gives a negligible radiative decay rate (about 10 7 times slower than that of bright excitons). Spin flip due to Zeeman effect in a sufficiently strong in-plane magnetic field can give a decay rate comparable to that due to the intrinsic interband spin–flip dipole.