Magnetic field mixing and splitting of bright and dark excitons in monolayer MoSe2

Abstract

Monolayers of semiconducting transition metal dichalcogenides (TMDCs) with unique spin-valley contrasting properties and remarkably strong excitonic effects continue to be a subject of intense research interests. These model 2D semiconductors feature two fundamental intravalley excitons species - optically accessible ' bright' excitons with anti-parallel spins and optically inactive 'dark' excitons with parallel spins. For applications exploiting radiative recombination of bright excitons or long lifetime dark excitons, it is essential to understand the radiative character of the exciton ground state and establish the energy separation between the lowest energy bright and dark excitons. Here, we report a direct spectroscopic measure of dark excitons in monolayer MoSe${}_2$ encapsulated in hexagonal boron nitride. By applying strong in-plane magnetic field, we induce mixing and splitting of bright and dark exciton branches, which enables an accurate spectroscopic determination of their energies. We confirm the bright character of the exciton ground state separated by a 1.5~meV gap from the higher energy dark exciton state, much smaller compared to the previous theoretical expectations. These findings provide critical information for further improvement of the accurate theoretical description of TMDCs electronic structure.

11 pages, 5 figures

References in corpus (4)

• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Dark excitons in transition metal dichalcogenides
• Polarization and time-resolved photoluminescence spectroscopy of excitons in MoSe2 monolayers

Cited by in corpus (7)

• Dipolar and magnetic properties of strongly absorbing hybrid interlayer excitons in pristine bilayer MoS${}_2$
• Localized Excitons in NbSe${}_2$-MoSe${}_2$ Heterostructures
• Rydberg series of dark excitons and the conduction band spin-orbit splitting in monolayer WSe${}_2$
• Exciton valley depolarization in monolayer transition-metal dichalcogenides
• Ultrafast pseudospin quantum beats in multilayer WSe${}_2$ and MoSe${}_2$
• Dynamics of resonantly excited excitons in MoSe${}_2$ and WS${}_2$ single-layers monitored with four-wave mixing
• Excitonic Transport and Intervalley Scattering in Exfoliated MoSe2 Monolayer Revealed by Four-Wave-Mixing Transient Grating Spectroscopy