Spin and valley dynamics of excitons in transition metal dichalcogenide monolayers

M. M. Glazov, E. L. Ivchenko, G. Wang, T. Amand, X. Marie, B. Urbaszek, B. L. Liu

Research output

56 Citations (Scopus)

Abstract

Monolayers of transition metal dichalcogenides, namely, molybdenum and tungsten disulfides and diselenides demonstrate unusual optical properties related to the spin-valley locking effect. Particularly, excitation of monolayers by circularly polarized light selectively creates electron-hole pairs or excitons in non-equivalent valleys in momentum space, depending on the light helicity. This allows studying the inter-valley dynamics of charge carriers and Coulomb complexes by means of optical spectroscopy. Here, we present a concise review of the neutral exciton fine structure and its spin and valley dynamics in monolayers of transition metal dichalcogenides. It is demonstrated that the long-range exchange interaction between an electron and a hole in the exciton is an efficient mechanism for rapid mixing between bright excitons made of electron-hole pairs in different valleys. We discuss the physical origin of the long-range exchange interaction and outline its derivation in both the electrodynamical and k·p approaches. We further present a model of bright exciton spin dynamics driven by an interplay between the long-range exchange interaction and scattering. Finally, we discuss the application of the model to describe recent experimental data obtained by time-resolved photoluminescence and Kerr rotation techniques. Kerr rotation dynamics at T=4K for a σ+ and σ- pump beam in WSe2. Inset: Schematics of the optical selection rules of the excitons photogenerated from charge carriers in K± valleys and their coupling induced by the long-range exchange interaction.

Original languageEnglish
Pages (from-to)2349-2362
Number of pages14
JournalPhysica Status Solidi (B) Basic Research
Volume252
Issue number11
DOIs
Publication statusPublished - 1 Jan 2015

Fingerprint

spin dynamics
Excitons
Transition metals
valleys
Monolayers
transition metals
Exchange interactions
excitons
disulfides
Charge carriers
Electrons
charge carriers
interactions
molybdenum disulfides
Spin dynamics
Tungsten
Molybdenum
circuit diagrams
Schematic diagrams
Light polarization

Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Glazov, M. M. ; Ivchenko, E. L. ; Wang, G. ; Amand, T. ; Marie, X. ; Urbaszek, B. ; Liu, B. L. / Spin and valley dynamics of excitons in transition metal dichalcogenide monolayers. In: Physica Status Solidi (B) Basic Research. 2015 ; Vol. 252, No. 11. pp. 2349-2362.
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Spin and valley dynamics of excitons in transition metal dichalcogenide monolayers. / Glazov, M. M.; Ivchenko, E. L.; Wang, G.; Amand, T.; Marie, X.; Urbaszek, B.; Liu, B. L.

In: Physica Status Solidi (B) Basic Research, Vol. 252, No. 11, 01.01.2015, p. 2349-2362.

Research output

TY - JOUR

T1 - Spin and valley dynamics of excitons in transition metal dichalcogenide monolayers

AU - Glazov, M. M.

AU - Ivchenko, E. L.

AU - Wang, G.

AU - Amand, T.

AU - Marie, X.

AU - Urbaszek, B.

AU - Liu, B. L.

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N2 - Monolayers of transition metal dichalcogenides, namely, molybdenum and tungsten disulfides and diselenides demonstrate unusual optical properties related to the spin-valley locking effect. Particularly, excitation of monolayers by circularly polarized light selectively creates electron-hole pairs or excitons in non-equivalent valleys in momentum space, depending on the light helicity. This allows studying the inter-valley dynamics of charge carriers and Coulomb complexes by means of optical spectroscopy. Here, we present a concise review of the neutral exciton fine structure and its spin and valley dynamics in monolayers of transition metal dichalcogenides. It is demonstrated that the long-range exchange interaction between an electron and a hole in the exciton is an efficient mechanism for rapid mixing between bright excitons made of electron-hole pairs in different valleys. We discuss the physical origin of the long-range exchange interaction and outline its derivation in both the electrodynamical and k·p approaches. We further present a model of bright exciton spin dynamics driven by an interplay between the long-range exchange interaction and scattering. Finally, we discuss the application of the model to describe recent experimental data obtained by time-resolved photoluminescence and Kerr rotation techniques. Kerr rotation dynamics at T=4K for a σ+ and σ- pump beam in WSe2. Inset: Schematics of the optical selection rules of the excitons photogenerated from charge carriers in K± valleys and their coupling induced by the long-range exchange interaction.

AB - Monolayers of transition metal dichalcogenides, namely, molybdenum and tungsten disulfides and diselenides demonstrate unusual optical properties related to the spin-valley locking effect. Particularly, excitation of monolayers by circularly polarized light selectively creates electron-hole pairs or excitons in non-equivalent valleys in momentum space, depending on the light helicity. This allows studying the inter-valley dynamics of charge carriers and Coulomb complexes by means of optical spectroscopy. Here, we present a concise review of the neutral exciton fine structure and its spin and valley dynamics in monolayers of transition metal dichalcogenides. It is demonstrated that the long-range exchange interaction between an electron and a hole in the exciton is an efficient mechanism for rapid mixing between bright excitons made of electron-hole pairs in different valleys. We discuss the physical origin of the long-range exchange interaction and outline its derivation in both the electrodynamical and k·p approaches. We further present a model of bright exciton spin dynamics driven by an interplay between the long-range exchange interaction and scattering. Finally, we discuss the application of the model to describe recent experimental data obtained by time-resolved photoluminescence and Kerr rotation techniques. Kerr rotation dynamics at T=4K for a σ+ and σ- pump beam in WSe2. Inset: Schematics of the optical selection rules of the excitons photogenerated from charge carriers in K± valleys and their coupling induced by the long-range exchange interaction.

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KW - Excitons

KW - Optical orientation

KW - Spin dynamics

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