Non-adiabatic Exciton Dynamics in van der Waals Heterostructures

The Journal of Physical Chemistry Letters, Год журнала: 2022, Номер 13(50), С. 11760 - 11769

Опубликована: Дек. 14, 2022

In this Perspective, we introduce a first-principles method that combines time-dependent density functional theory with non-adiabatic molecular dynamics (NAMD) to explore exciton in two-dimensional (2D) van der Waals (vdW) heterostructures. The theoretical foundation and computational efficiency of the are discussed compared those related methods (e.g., GW-BSE). Using three 2D vdW heterostructures as examples, demonstrate proposed can provide reliable description many-body electron–hole interactions crucial dynamics. With much lower costs than GW-BSE method, represents particularly promising tool probe solids. Moreover, find NAMD simulations widely used literature cannot capture excitonic effect materials often yield incorrect results because they formulated single-particle picture. instances where picture fails pointed out contrasted simulation results.

Язык: Английский

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Pseudo-heterostructure and condensation of 1D moiré excitons in twisted phosphorene bilayers

Science Advances, Год журнала: 2023, Номер 9(29)

Опубликована: Июль 21, 2023

Heterostructures are not expected to form in a single homogeneous material. Here, we show that planar pseudo-heterostructures could emerge twisted bilayer of phosphorene (tbP), driving in-plane energy and charge transfer. The formation moiré superlattices combined with electronic anisotropy tbPs yields one-dimensional (1D) excitons long radiative nonradiative lifetimes, large binding energies, deep potentials. Low-frequency phonons dynamic potentials revealed be responsible for the energy/charge transfer exciton dynamics. 1D predicted exhibit Bose-Einstein condensation at high temperatures may lead exotic Tonks-Girardeau Bose gases.

Язык: Английский

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Correlation-driven nonequilibrium exciton site transition in a WSe2/WS2 moiré supercell

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Апрель 17, 2024

Abstract Moiré superlattices of transition metal dichalcogenides offer a unique platform to explore correlated exciton physics with optical spectroscopy. Whereas the spatially modulated potentials evoke that resonances are distinct depending on site in moiré supercell, there have been no clear demonstration how excitons trapped different sites dynamically interact doped carriers; so far exciton-electron dynamic interactions were presumed be site-dependent. Thus, transient emergence nonequilibrium correlations open questions, but existing studies limited steady-state measurements. Here we report experimental fingerprints site-dependent under continuous-wave as well ultrashort excitations. In near-zero angle-aligned WSe 2 /WS heterobilayers, observe intriguing polarization switching and strongly enhanced Pauli blocking near Mott insulating state, dictating dominant correlation-driven effects. When twist angle is 60°, such observed, suggesting strong dependence atomic registry supercell configuration. Our door largely unexplored superlattices.

Язык: Английский

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Brightening of Optical Forbidden Interlayer Quantum Emitters in WSe₂ Homobilayers

ACS Nano, Год журнала: 2025, Номер unknown

Опубликована: Фев. 19, 2025

Interlayer excitons (IXs) in layered van der Waals materials are promising for quantum technologies and fundamental studies such as exciton-polariton condensation due to their large permanent dipole moments. However, indirect bandgap optical transition through the Q-K channel renders them momentum forbidden thus less relevant applications. Here, we demonstrate a method brightening transitions from IX emitters (QEs) 2H-stacked bilayer WSe2 by simultaneously employing local strain plasmonic nanocavity coupling. Initially, long T1 lifetimes up 140 ns indicative of transitions. Magneto-photoluminescence data show striking bimodal distribution g-factors between mono- QEs, with well-defined value g = 9.5 IX, highlighting nature decoupling variations. In addition, angle-resolved PL measurements reveal that curvature on nanostressor induces orientation tilt affecting cavity By embedding these strained QEs into cavities, achieve 10-fold increase emission intensity 24-fold enhancement lifetime best case (12-fold average), leading bright single-photon rates 1.45 ± 0.1 MHz first lens. Moreover, demonstrated allowed push wavelength reliably around 810 nm enables free-space communication.

Язык: Английский

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Ultrafast Electronic Dynamics in Anisotropic Indirect Interlayer Excitonic States of Monolayer WSe₂/ReS₂ Heterojunctions

Nano Letters, Год журнала: 2023, Номер 23(18), С. 8643 - 8649

Опубликована: Сен. 6, 2023

Understanding ultrafast electronic dynamics of the interlayer excitonic states in atomically thin transition metal dichalcogenides is importance engineering valleytronics and developing integrated circuits. In this work, we experimentally explored indirect monolayer type II WSe2/ReS2 heterojunctions using time-resolved photoemission electron microscopy, which reveals its anisotropic behavior. The cooling decay excited-state electrons exhibit significant linear dichroism. ab initio theoretical calculations provide unambiguous evidence that dichroism result primarily associated with nonradiative recombination states. Measuring energy spectra, have further revealed evolution findings important implications for controlling moiré effects designing optoelectronic devices.

Язык: Английский

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Excitonic Insulators and Superfluidity in Two-Dimensional Bilayers without External Fields

The Journal of Physical Chemistry Letters, Год журнала: 2023, Номер 14(9), С. 2277 - 2283

Опубликована: Фев. 24, 2023

We explore a new platform for realizing excitonic insulators, namely van der Waals (vdW) bilayers comprising two-dimensional Janus materials. In previous studies, type II heterobilayers have been brought to the insulating regime by tuning band alignment using external gates. contrast, presented here represent intrinsic insulators. first conduct ab initio calculations obtain quasiparticle structures, screened Coulomb interaction, and interlayer exciton binding energies of bilayers. These initio-derived quantities are then used construct BCS-like Hamiltonian condensate. By solving mean-field gap equation, we identify 16 vdW with ground states superfluid properties. Our expose class advanced materials that likely exhibit novel phases at low temperatures highlight subtle competition between hybridization, spin-orbit coupling, dielectric screening governs their

Язык: Английский

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0D-2D heterostructure for making very large quantum registers using ‘itinerant’ Bose-Einstein condensate of excitons

Materials Today Electronics, Год журнала: 2023, Номер 4, С. 100039 - 100039

Опубликована: Июнь 1, 2023

Presence of coherent 'resonant' tunneling in quantum dot (zero-dimensional) - well (two-dimensional) heterostructure is necessary to explain the collective oscillations average electrical polarization excitonic dipoles over a macroscopically large area. This was measured using photo excited capacitance as function applied voltage bias. Resonant this definitely requires momentum space narrowing charge carriers inside and that associated indirect excitons, which indicates bias dependent 'itinerant' Bose-Einstein condensation excitons. Observation periodic variations negative points in-plane coulomb correlations mediated by long range spatial ordering indirect, dipolar Enhanced contrast interference beats waves even under white light observed Rabi area also support presence density driven having order. Periodic (absence) splitting peaks photocapacitance spectra demonstrate coupling (decoupling) between energy levels dots with biases, can potentially be used for gate operations. All these observations point experimental control large, state two-component condensate excitons heterostructure. Therefore, principle, millions two-level qubits intertwined fabricate registers such hybrid controlling local electric fields varying photoexcitation intensities overlapping spots.

Язык: Английский

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Excitons and excitonic materials

MRS Bulletin, Год журнала: 2024, Номер 49(9), С. 852 - 861

Опубликована: Сен. 1, 2024

Язык: Английский

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Small exciton effective mass in quintuple-layer Bi2Se2Te : A material platform towards high-temperature excitonic condensate

Physical review. B./Physical review. B, Год журнала: 2024, Номер 110(5)

Опубликована: Авг. 15, 2024

Using first-principles simulations combined with many-body calculations, we show that two-dimensional free-standing quintuple-layer (QL) ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{2}\mathrm{Te}$ is an inversion-symmetric monolayer expected to achieve spatially indirect exciton large radius, small effective mass, and long lifetime. Such system theoretically predicted be a promising platform for realizing excitonic Bose-Einstein condensation superfluid due its high phase transition temperatures of $\ensuremath{\sim}257$ $\ensuremath{\sim}64.25$ K the degeneracy superfluid, respectively. The importance spin-orbit coupling revealed, angular momentum selection rules photon absorption are discussed. This finding suggests potential QL exotic bosonic bound states provides as tantalizing high-temperature probe physics.

Язык: Английский

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Progress and prospects of Moiré superlattices in twisted TMD heterostructures

Nano Research, Год журнала: 2024, Номер unknown

Опубликована: Сен. 6, 2024

Язык: Английский

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