Exciton landscape in van der Waals heterostructures

Hagel, Joakim; Brem, Samuel; Linderälv, Christopher; Erhart, Paul; Malić, Ermin

doi:10.1103/physrevresearch.3.043217

Cited by 36 publications

(66 citation statements)

References 54 publications

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“…1(c)]. Phononassisted tunneling leads to the relaxation of the optically pumped intralayer excitons into R h h exciton states [32]. These states show similar optical selection rules and a g factor of approximately −6.2 [31] [see Fig.…”

Section: Theoretical Modelmentioning

confidence: 99%

Interlayer exciton valley polarization dynamics in large magnetic fields

et al. 2022

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Section: Theoretical Modelmentioning

confidence: 99%

Interlayer exciton valley polarization dynamics in large magnetic fields

et al. 2022

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“…2 For the purpose of this paper, we consider a simpler case of untwisted structures to disentangle the effect of electrostatic effects and hybridization. 11 To this end, we use the exciton density matrix formalism [12][13][14] and calculate the exciton energies for untwisted van-der-Waals heterostructures by first formulating a Hamiltonian in second quantization for the interaction free electronic energies…”

Section: Methodsmentioning

confidence: 99%

The moiré potential in twisted transition metal dichalcogenide bilayers

Linderälv¹,

Hagel²,

Brem³

et al. 2022

Preprint

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Moiré superlattices serve as a playground for emerging phenomena, such as localization of band states, superconductivity, and localization of excitons. These superlattices are large and are often modeled in the zero angle limit, which obscures the effect of finite twist angles. Here, by means of first-principles calculations we quantify the twist-angle dependence of the moiré potential in the MoS2 homobilayer and identify the contributions from the constituent elements of the moiré potential. Furthermore, by considering the zero-angle limit configurations, we show that the moiré potential is rather homogeneous across the transition metal dichalcogenides (TMDs) and briefly discuss the separate effects of potential shifts and hybridization on the bilayer hybrid excitons. We find that the moiré potential in TMDs exhibits both an electrostatic component and a hybridization component, which are intertwined and have different relative strengths in different parts of the Brillouin zone. The electrostatic component of the moiré potential is a varying dipole field, which has a strong twist angle dependence. In some cases, the hybridization component can be interpreted as a tunneling rate but the interpretation is not generally applicable over the full Brillouin zone.

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“…figure 1 (c). Phonon-assisted tunneling leads to the relaxation of the optically pumped intralayer excitons into R h h exciton states 32 . These states show similar optical selection rules and a g-factor of approximately -6.2 31 , cf.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…figure 1 (g). Phonon-assisted tunneling mediates the relaxation of the optically pumped WSe 2 excitons to interlayer H X h excitons 32 . These excitons have similar optical selection rules as the WSe 2 layer and a g-factor of about -12.6 31 , cf.…”

Section: Theoretical Modelmentioning

confidence: 99%

Interlayer exciton valley polarization dynamics in large magnetic fields

Holler,

Selig,

Kempf

et al. 2021

Preprint

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In van der Waals heterostructures (HS) consisting of stacked MoSe2 and WSe2 monolayers, optically bright interlayer excitons (ILE) can be observed when the constituent layers are crystallographically aligned. The symmetry of the monolayers allows for two different types of alignment, in which the momentum-direct interlayer transitions are either valley-conserving (R-type alignment) or changing the valley index (H-type anti-alignment).Here, we study the valley polarization dynamics of ILE in magnetic fields up to 30 Tesla by time-resolved photoluminescence (PL). For all ILE types, we find a finite initial PL circular degree of polarization (DoP ) after unpolarized excitation in applied magnetic fields. For ILE in H-type HS, we observe a systematic increase of the PL DoP with time in applied magnetic fields, which saturates at values close to unity for the largest fields. By contrast, for ILE in R-type HS, the PL DoP shows a decrease and a zero crossing before saturating with opposite polarization. This unintuitive behavior can be explained by a model considering the different ILE states in H-and R-type HS and their selection rules coupling PL helicity and valley polarization.

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Exciton landscape in van der Waals heterostructures

Cited by 36 publications

References 54 publications

Interlayer exciton valley polarization dynamics in large magnetic fields

Interlayer exciton valley polarization dynamics in large magnetic fields

The moiré potential in twisted transition metal dichalcogenide bilayers

Interlayer exciton valley polarization dynamics in large magnetic fields

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