Electrically Tunable Valley Dynamics in Twisted 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>WSe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>/</mml:mo><mml:msub><mml:mrow><mml:mi>WSe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>
 Bilayers

Scuri, Giovanni; Andersen, Trond I.; Zhou, You; Wild, Dominik S.; Sung, Jiho; Gelly, Ryan J.; Bérubé, Damien; Heo, Heeok; Shao, Linbo; Joe, Andrew Y.; Valdivia, Andrés M. Mier; Taniguchi, Takashi; Watanabe, Kenji; Lončar, Marko; Kim, Philip; Lukin, Mikhail D.; Park, Hongkun

doi:10.1103/physrevlett.124.217403

Cited by 111 publications

(76 citation statements)

References 72 publications

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“…The absolute DOCP is greatly suppressed at −60 V (p-doping), but enhanced at 60 V (n-doping). This phenomenon has been reported by Scuri and coworkers, and is attributed to changes in valley-depolarizationtime caused by electron/hole doping 41 . Similarly, we believe our observation can also ascribed to the charge doping from external applied bias and chemical doping (Fig.…”

Section: Valleytronic Hysteresis Of the Ixssupporting

confidence: 73%

Interlayer-Exciton Based Nonvolatile Valleytronic Memory

Ye¹,

Shen²,

Ren³

et al. 2020

Preprint

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Analogous to conventional charge-based electronics, valleytronics aims at encoding data via valley degree of freedom, enabling new routes for information processing. Long-lived interlayer excitons (IXs) in van der Waals heterostructures (HSs) stacked by transition metal dichalcogenides (TMDs) carry valley-polarized information and thus would find promising applications in valleytronic devices. Although great progress of IX based valleytronic devices has been achieved, nonvolatile valleytronic memories are still challenging. Here, we demonstrate IX based nonvolatile valleytronic memory in a WS2/WSe2 HS. The emission characteristics of IX exhibit a large excitonic/valleytronic hysteresis upon cyclic-voltage sweeping. Importantly, IX emission can be electrically switched between a bright state and a dark state with large light-intensity and helicity contrast of about 1.7 and 1.8, respectively, which can be ascribed to the chemical-doping of O2/H2O redox couple between TMDs and substrate. Taking advantage of the large hysteresis, IX can be utilized for manipulating and nonvolatile storing valley information and IX based nonvolatile valleytronic memory has been successfully demonstrated. These findings open up an avenue for nonvolatile valleytronic memory and would motivate more investigations on valleytronic devices.

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Section: Valleytronic Hysteresis Of the Ixssupporting

confidence: 73%

Interlayer-Exciton Based Nonvolatile Valleytronic Memory

Ye¹,

Shen²,

Ren³

et al. 2020

Preprint

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“…Decreasing the twist angle to 30°increases the interlayer distance and shifts X to the blue 25,26 , i.e., towards the energy of the A-exciton PL of single-layer WSe 2 20 . For the present analysis, we ignore signatures of intervalley excitons 6,27,28 (marked by an asterisk in Fig. 1d).…”

Section: Resultsmentioning

confidence: 99%

Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors

et al. 2021

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Twist-engineering of the electronic structure in van-der-Waals layered materials relies predominantly on band hybridization between layers. Band-edge states in transition-metal-dichalcogenide semiconductors are localized around the metal atoms at the center of the three-atom layer and are therefore not particularly susceptible to twisting. Here, we report that high-lying excitons in bilayer WSe2 can be tuned over 235 meV by twisting, with a twist-angle susceptibility of 8.1 meV/°, an order of magnitude larger than that of the band-edge A-exciton. This tunability arises because the electronic states associated with upper conduction bands delocalize into the chalcogenide atoms. The effect gives control over excitonic quantum interference, revealed in selective activation and deactivation of electromagnetically induced transparency (EIT) in second-harmonic generation. Such a degree of freedom does not exist in conventional dilute atomic-gas systems, where EIT was originally established, and allows us to shape the frequency dependence, i.e., the dispersion, of the optical nonlinearity.

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“…Recently, twisted bilayer graphene [2][3][4][5][6] and other van der Waals materials stacked atop each other at a twist [7][8][9][10][11][12][13] have been proposed as material realizations of two-dimensional correlated physics that afford an unprecedented level of control. Previous studies concentrate on few-layer films featuring a 60 or 120 rotational symmetry stacked at a twist.…”

mentioning

confidence: 99%

One-dimensional flat bands in twisted bilayer germanium selenide

et al. 2020

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Experimental advances in the fabrication and characterization of few-layer materials stacked at a relative twist of small angle have recently shown the emergence of flat energy bands. As a consequence electron interactions become relevant, providing inroads into the physics of strongly correlated two-dimensional systems. Here, we demonstrate by combining large scale ab initio simulations with numerically exact strong correlation approaches that an effective one-dimensional system emerges upon stacking two twisted sheets of GeSe, in marked contrast to all moiré systems studied so far. This not only allows to study the necessarily collective nature of excitations in one dimension, but can also serve as a promising platform to scrutinize the crossover from two to one dimension in a controlled setup by varying the twist angle, which provides an intriguing benchmark with respect to theory. We thus establish twisted bilayer GeSe as an intriguing inroad into the strongly correlated physics of lowdimensional systems.

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Electrically Tunable Valley Dynamics in Twisted WSe2/WSe2 Bilayers

Cited by 111 publications

References 72 publications

Interlayer-Exciton Based Nonvolatile Valleytronic Memory

Interlayer-Exciton Based Nonvolatile Valleytronic Memory

Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors

One-dimensional flat bands in twisted bilayer germanium selenide

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