Probing many-body interactions in monolayer transition-metal dichalcogenides

Tuan, Dinh Van; Scharf, Benedikt; Wang, Zefang; Shan, Jie; Mak, Kin Fai; Žutić, Igor; Dery, Hanan

doi:10.1103/physrevb.99.085301

Cited by 76 publications

(73 citation statements)

References 91 publications

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“…We will present a compact analytical model in Sec. 9 that shows how the coupling of neutral excitons to shortwave plasmons gives rise to both observed phenomena in ML-TMDs [45].…”

Section: Excitons In the Presence Of Long-wavelength Charge Excitationsmentioning

confidence: 84%

“…Next, we evaluate the Coulomb-hole energy due to long-wavelength plasma excitations [Eq. (45)]. It is by far the dominant contribution to the BGR.…”

Section: Bgr Due To Intravalley Coulomb Excitationsmentioning

confidence: 99%

“…(91), but with indirect exciton parameters. Finally, Mq is the exciton-plasmon interaction matrix element [45],…”

Section: The Coupling Between Intervalley Plasmons and Excitonsmentioning

confidence: 99%

“…9.1.3. Binding energies of direct and indirect excitons in charge-neutrality conditions: |E d | and |E i | at zero charge density are calculated by the stochastic variational method [45,74]. Following Ref.…”

Section: Broadening Parametersmentioning

confidence: 99%

“…Following Ref. [45], the binding energies in charge neutrality conditions are |E d | = 178 meV and |E i | = 195 meV in ML-WSe 2 embedded in hBN. The respective values in embedded ML-MoSe 2 are |E d | = 203 meV and |E i | = 211 meV.…”

Section: Broadening Parametersmentioning

confidence: 99%

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Dynamical screening in monolayer transition-metal dichalcogenides and its manifestations in the exciton spectrum

Scharf

Tuan

Žutić

et al. 2019

J. Phys.: Condens. Matter

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Monolayer transition-metal dichalcogenides (ML-TMDs) offer exciting opportunities to test the manifestations of many-body interactions through changes in the charge density. The two-dimensional character and reduced screening in ML-TMDs lead to the formation of neutral and charged excitons with binding energies orders of magnitude larger than those in conventional bulk semiconductors. Tuning the charge density by a gate voltage leads to profound changes in the optical spectra of excitons in ML-TMDs. On the one hand, the increased screening at large charge densities should result in a blueshift of the exciton spectral lines due to reduction in the binding energy. On the other hand, exchange and correlation effects that shrink the band-gap energy at elevated charge densities (band-gap renormalization) should result in a redshift of the exciton spectral lines. While these competing effects can be captured through various approximations that model long-wavelength charge excitations in the Bethe-Salpeter Equation, we show that a novel coupling between excitons and shortwave charge excitations is essential to resolve several experimental puzzles.Unlike ubiquitous and well-studied plasmons, driven by collective oscillations of the background charge density in the long-wavelength limit, we discuss the emergence of shortwave plasmons that originate from the short-range Coulomb interaction through which electrons transition between the K and −K valleys. The shortwave plasmons have a finite energy-gap because of the removal of spin-degeneracy in both the valence-arXiv:1801.06217v2 [cond-mat.mtrl-sci] 2. Properties of monolayer transition-metal dichalcogenides ML-TMDs are direct band-gap semiconductors with the conduction band and valence band edges at the K and K = −K points [19]. These time-reversed points define two separate low-energy pockets/valleys in the Brillouin zone. Due to the lack of space inversion symmetry and strong spin-orbit coupling arising from the d orbitals of the transition-metal atoms, the spin degeneracy in these valleys is lifted [24], as shown in Figs. 1(a,c). Whereas the spin splitting ∆ c in the conduction band is typically at most a few 10s of meV, the spin splitting in the valence band can be several 100s meV [24,54,55,56,57]. There are two important aspects to this band structure: First, timereversal symmetry results in a coupling between the spin and valley degrees of freedom, such that the spin ordering in opposite valleys is reversed as illustrated in Figs. 1(a,c). Second, the spin ordering of the conduction band in Mo-based compounds is opposite to the one in W-based compounds, as can be seen by comparing Figs. 1(a) and (c) [24,57,58]. This difference will be shown below to have profound consequences on their optical properties. Due to the large spin-splitting energy of the valence band, one can distinguish between two different series of neutral excitons in absorption experiments: One series involving the top valleys in the valence band, usually denoted as A excitons, and one involving it...

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“…We will present a compact analytical model in Sec. 9 that shows how the coupling of neutral excitons to shortwave plasmons gives rise to both observed phenomena in ML-TMDs [45].…”

Section: Excitons In the Presence Of Long-wavelength Charge Excitationsmentioning

confidence: 84%

“…Next, we evaluate the Coulomb-hole energy due to long-wavelength plasma excitations [Eq. (45)]. It is by far the dominant contribution to the BGR.…”

Section: Bgr Due To Intravalley Coulomb Excitationsmentioning

confidence: 99%

“…(91), but with indirect exciton parameters. Finally, Mq is the exciton-plasmon interaction matrix element [45],…”

Section: The Coupling Between Intervalley Plasmons and Excitonsmentioning

confidence: 99%

Section: Broadening Parametersmentioning

confidence: 99%

Section: Broadening Parametersmentioning

confidence: 99%

See 3 more Smart Citations

Dynamical screening in monolayer transition-metal dichalcogenides and its manifestations in the exciton spectrum

Scharf

Tuan

Žutić

et al. 2019

J. Phys.: Condens. Matter

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Atomically Thin van der Waals Semiconductors—A Theoretical Perspective

Gies

Steinhoff

2021

Laser & Photonics Reviews

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2D semiconductors and their heterostructures have developed into a flourishing research field. A more or less simultaneous start of experimental and theoretical developments has led to continuous advancements in both branches of physics that continue to benefit from one another in an exemplary manner. This article gives an overview of the theoretical advancements that have resulted from a decade of research on 2D van der Waals materials and reviews current theoretical methods, focussing on exciton-plasma balance, excited-state optics, and laser physics.

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Multiphonon Raman Scattering in Transition Metal Dichalcogenide Double Layers

Wang

Deng

Xiao

et al. 2020

Physica Rapid Research Ltrs

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Herein, multiphonon Raman scattering assisted by the interlayer excitons in double transition metal chalcogenide (TMD) layers based on the Huang–Rhys's model is studied. The processes of multiple longitudinal optical (LO) phonons Raman scattering are presented due to the strong exciton–LO phonon coupling. It is found that the Raman scattering intensity and orders of LO phonon overtones depend on the obtained value of Huang–Rhys factor, which can be tuned obviously by the strength of exciton–LO phonon coupling and interlayer distance between two TMD layers. Meanwhile, temperature dependence of scattering intensities for different orders of LO phonon overtones in the multiphonon processes is discussed. The theoretical results provide significant insight not only for the analysis of multiphonon Raman spectroscopy in experiments, but also for the modulation of optical properties in a series of TMD double layers and Van der Waals heterostructures.

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Probing many-body interactions in monolayer transition-metal dichalcogenides

Cited by 76 publications

References 91 publications

Dynamical screening in monolayer transition-metal dichalcogenides and its manifestations in the exciton spectrum

Dynamical screening in monolayer transition-metal dichalcogenides and its manifestations in the exciton spectrum

Atomically Thin van der Waals Semiconductors—A Theoretical Perspective

Multiphonon Raman Scattering in Transition Metal Dichalcogenide Double Layers

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