Controlling Excitons in an Atomically Thin Membrane with a Mirror

Zhou, You; Scuri, Giovanni; Sung, Jiho; Gelly, Ryan J.; Wild, Dominik S.; Greve, Kristiaan De; Joe, Andrew Y.; Taniguchi, Takashi; Watanabe, Kenji; Kim, Philip; Lukin, Mikhail D.; Park, Hongkun

doi:10.1103/physrevlett.124.027401

Cited by 75 publications

(78 citation statements)

References 67 publications

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“…In a moiré lattice, both the oscillator strength and dipole interactions depend sensitively on, and can be tuned by the twist angle. The twisted WS 2 /MoSe 2 bilayers may provide tunable, nonlinear, exciton and polariton lattice systems for exotic states of matter, such as topological excitons and exciton crystals, with novel applications in nanophotonics and quantum information science 10 – 13 , 38 – 53 .…”

Section: Discussionmentioning

confidence: 99%

Twist-angle dependence of moiré excitons in WS2/MoSe2 heterobilayers

et al. 2020

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Moiré lattices formed in twisted van der Waals bilayers provide a unique, tunable platform to realize coupled electron or exciton lattices unavailable before. While twist angle between the bilayer has been shown to be a critical parameter in engineering the moiré potential and enabling novel phenomena in electronic moiré systems, a systematic experimental study as a function of twist angle is still missing. Here we show that not only are moiré excitons robust in bilayers of even large twist angles, but also properties of the moiré excitons are dependant on, and controllable by, the moiré reciprocal lattice period via twist-angle tuning. From the twist-angle dependence, we furthermore obtain the effective mass of the interlayer excitons and the electron inter-layer tunneling strength, which are difficult to measure experimentally otherwise. These findings pave the way for understanding and engineering rich moiré-lattice induced phenomena in angle-twisted semiconductor van der Waals heterostructures.

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Section: Discussionmentioning

confidence: 99%

Twist-angle dependence of moiré excitons in WS2/MoSe2 heterobilayers

et al. 2020

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“…Strain-mediated coupling could also be employed to manipulate the rich excitonic manifolds in transition metal dichalcogenides 57 , as well as the single photon emitters they can host 58 , 59 . More broadly, light absorption and emission could be controlled electro-mechanically in nanoresonators made from custom-designed van der Waals heterostructures 60 . Going one step further, with the emergence of 2D materials featuring robust magnetic order and topological phases 61 , that can be probed using optical spectroscopy, we foresee new possibilities to explore and harness phase transitions using nanomechanical resonators based on 2D materials 62 , 63 .…”

Section: Discussionmentioning

confidence: 99%

Dynamically-enhanced strain in atomically thin resonators

et al. 2020

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Graphene and related two-dimensional (2D) materials associate remarkable mechanical, electronic, optical and phononic properties. As such, 2D materials are promising for hybrid systems that couple their elementary excitations (excitons, phonons) to their macroscopic mechanical modes. These built-in systems may yield enhanced strain-mediated coupling compared to bulkier architectures, e.g., comprising a single quantum emitter coupled to a nano-mechanical resonator. Here, using micro-Raman spectroscopy on pristine monolayer graphene drums, we demonstrate that the macroscopic flexural vibrations of graphene induce dynamical optical phonon softening. This softening is an unambiguous fingerprint of dynamically-induced tensile strain that reaches values up to ≈4 × 10−4 under strong non-linear driving. Such non-linearly enhanced strain exceeds the values predicted for harmonic vibrations with the same root mean square (RMS) amplitude by more than one order of magnitude. Our work holds promise for dynamical strain engineering and dynamical strain-mediated control of light-matter interactions in 2D materials and related heterostructures.

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“…As the exciton linewidth in TMDC monolayers is mainly dominated by radiative broadening [7-9, 47, 48], the control of the exciton spontaneous lifetime due to the cavity effect evidenced in Fig. 2(a) and (b) also yields a tuning of the exciton linewidth [49,50].…”

Section: Samples and Setup We Have Investigated Mosementioning

confidence: 99%

Control of the Exciton Radiative Lifetime in van der Waals Heterostructures

et al. 2019

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Optical properties of atomically thin transition metal dichalcogenides are controlled by robust excitons characterized by a very large oscillator strength. Encapsulation of monolayers such as MoSe2 in hexagonal boron nitride (hBN) yields narrow optical transitions approaching the homogenous exciton linewidth. We demonstrate that the exciton radiative rate in these van der Waals heterostructures can be tailored by a simple change of the hBN encapsulation layer thickness as a consequence of the Purcell effect. The time-resolved photoluminescence measurements show that the neutral exciton spontaneous emission time can be tuned by one order of magnitude depending on the thickness of the surrounding hBN layers. The inhibition of the radiative recombination can yield spontaneous emission time up to 10 ps. These results are in very good agreement with the calculated recombination rate in the weak exciton-photon coupling regime. The analysis shows that we are also able to observe a sizeable enhancement of the exciton radiative decay rate. Understanding the role of these electrodynamical effects allow us to elucidate the complex dynamics of relaxation and recombination for both neutral and charged excitons.

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Controlling Excitons in an Atomically Thin Membrane with a Mirror

Cited by 75 publications

References 67 publications

Twist-angle dependence of moiré excitons in WS2/MoSe2 heterobilayers

Twist-angle dependence of moiré excitons in WS2/MoSe2 heterobilayers

Dynamically-enhanced strain in atomically thin resonators

Control of the Exciton Radiative Lifetime in van der Waals Heterostructures

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