Optical properties of uniaxially strained graphene on transition metal dichalcogenide substrate

2018 ◽  
Vol 32 (13) ◽  
pp. 1850164 ◽  
Author(s):  
Partha Goswami
Keyword(s):  
Transition Metal ◽  
Strain Field ◽  
Graphene Monolayer ◽  
Transition Metal Dichalcogenide ◽  
Field Frequency ◽  
Long Wavelength ◽  
Strained Graphene ◽  
Valley Polarization ◽  
Doped Graphene ◽  
Spin Degeneracy

The uniaxially strained graphene monolayer on transition metal dichalcogenide (GrTMD) substrate, constituting a van der Waals heterostructure (vdWH), is found to possess unusual intra-band plasmon dispersion ([Formula: see text]) with stronger incarceration compared to that of a standalone, doped graphene for finite doping in the long wavelength limit. The intra-band absorbance of GrTMD is found to be an increasing (decreasing) function of the strain field (frequency) at a given frequency (strain field). It is also observed that whereas the strain field is responsible for the valley polarization, a Rashba coupling-dependent pseudo Zeeman term arising due to the interplay of substrate-induced interactions is found to bring about the spin degeneracy lifting and the gate voltage tunable spin polarization. The latter turns out to be inversely proportional to the square root of the carrier concentration.

Negative Valley Polarization in Doped Monolayer MoSe2

2021 ◽  
Author(s):  
Yueh-Chun Wu ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
Jun Yan
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenide ◽  
Optical Generation ◽  
Valley Polarization

Monolayer molybdenum di-selenide (1L-MoSe2) stands out in the transition metal dichalcogenide family of materials as an outlier where optical generation of valley polarization is inefficient. Here we show that using...

scholarly journals Sulfur-doped graphene/transition metal dichalcogenide heterostructured hybrids with electrocatalytic activity toward the hydrogen evolution reaction

2019 ◽  
Vol 1 (4) ◽  
pp. 1489-1496 ◽  
Author(s):  
Antonia Kagkoura ◽  
Mario Pelaez-Fernandez ◽  
Raul Arenal ◽  
Nikos Tagmatarchis
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Transition Metal Dichalcogenide ◽  
Doped Graphene

The preparation of SG/MoS2 and SG/WS2 heterostructured hybrids with high electrocatalytic activity towards the HER is accomplished.

scholarly journals Valley-selective directional emission from a transition-metal dichalcogenide monolayer mediated by a plasmonic nanoantenna

2018 ◽  
Vol 9 ◽  
pp. 780-788 ◽  
Author(s):  
Haitao Chen ◽  
Mingkai Liu ◽  
Lei Xu ◽  
Dragomir N Neshev
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Information Storage ◽  
Transition Metal Dichalcogenide ◽  
Point Dipole ◽  
Antenna Structure ◽  
Direct Emission ◽  
Valley Polarization ◽  
Potential Applications ◽  
Metal Dichalcogenides

Background: Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) with intrinsically crystal inversion-symmetry breaking have shown many advanced optical properties. In particular, the valley polarization in 2D TMDCs that can be addressed optically has inspired new physical phenomena and great potential applications in valleytronics. Results: Here, we propose a TMDC–nanoantenna system that could effectively enhance and direct emission from the two valleys in TMDCs into diametrically opposite directions. By mimicking the emission from each valley of the monolayer of WSe2 as a chiral point-dipole emitter, we demonstrate numerically that the emission from different valleys is directed into opposite directions when coupling to a double-bar plasmonic nanoantenna. The directionality derives from the interference between the dipole and quadrupole modes excited in the two bars, respectively. Thus, we could tune the emission direction from the proposed TMDC–nanoantenna system by tuning the pumping without changing the antenna structure. Furthermore, we discuss the general principles and the opportunities to improve the average performance of the nanoantenna structure. Conclusion: The scheme we propose here can potentially serve as an important component for valley-based applications, such as non-volatile information storage and processing.

scholarly journals Phenomenological model for long-wavelength optical modes in transition metal dichalcogenide monolayer

2021 ◽  
Vol 103 (23) ◽  
Author(s):  
C. Trallero-Giner ◽  
E. Menéndez-Proupin ◽  
E. Suárez Morell ◽  
R. Pérez-Álvarez ◽  
Darío G. Santiago-Pérez
Keyword(s):  
Transition Metal ◽  
Phenomenological Model ◽  
Transition Metal Dichalcogenide ◽  
Long Wavelength ◽  
Optical Modes

scholarly journals Experimental observation of topological Z2 exciton-polaritons in transition metal dichalcogenide monolayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mengyao Li ◽  
Ivan Sinev ◽  
Fedor Benimetskiy ◽  
Tatyana Ivanova ◽  
Ekaterina Khestanova ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide ◽  
Strong Light ◽  
Strongly Coupled ◽  
Exciton Polaritons ◽  
Valley Polarization ◽  
Topological States ◽  
Metal Dichalcogenides ◽  
Quantum Science

AbstractThe rise of quantum science and technologies motivates photonics research to seek new platforms with strong light-matter interactions to facilitate quantum behaviors at moderate light intensities. Topological polaritons (TPs) offer an ideal platform in this context, with unique properties stemming from resilient topological states of light strongly coupled with matter. Here we explore polaritonic metasurfaces based on 2D transition metal dichalcogenides (TMDs) as a promising platform for topological polaritonics. We show that the strong coupling between topological photonic modes of the metasurface and excitons in TMDs yields a topological polaritonic Z2 phase. We experimentally confirm the emergence of one-way spin-polarized edge TPs in metasurfaces integrating MoSe2 and WSe2. Combined with the valley polarization in TMD monolayers, the proposed system enables an approach to engage the photonic angular momentum and valley and spin of excitons, offering a promising platform for photonic/solid-state interfaces for valleytronics and spintronics.

scholarly journals Valley Orientation of Electrons and Excitons in Atomically Thin Transition Metal Dichalcogenide Monolayers (Brief Review)

JETP Letters ◽  
2021 ◽  
Vol 113 (1) ◽  
pp. 7-17
Author(s):  
M. M. Glazov ◽  
E. L. Ivchenko
Keyword(s):  
Transition Metal ◽  
Band Structure ◽  
Second Harmonic ◽  
Polarized Light ◽  
Charge Carriers ◽  
Photon Absorption ◽  
Transition Metal Dichalcogenide ◽  
Optical Orientation ◽  
Circularly Polarized Light ◽  
Valley Polarization

The main aspects of physical phenomena associated with the optical orientation of the spin and valley degrees of freedom in transition metal dichalcogenide monolayers and in van der Waals heterostructures based on them have been briefly reviewed. Owing to features of the band structure and spin–orbit coupling in such systems, circularly polarized light induces optical transitions in different valleys K+ and K– of the Brillouin zone; consequently, the optical orientation of charge carriers and excitons is accompanied by their valley polarization. The main features of the band structure of transition metal dichalcogenide monolayers, excitonic effects, and results of theoretical studies of the valley orientation of excitons and electrons at one-photon absorption have been reported. The linear–circular dichroism and valley orientation of free charge carriers and excitons at multiphoton absorption have been studied. Effects associated with the trigonal symmetry of monolayers, including the inversion of valley polarization at two-photon transitions and the second harmonic generation, have been discussed. The considered theoretical models have been illustrated by experimental data.

scholarly journals Room-Temperature Valley Polarization and Coherence in Transition Metal Dichalcogenide–Graphene van der Waals Heterostructures

ACS Photonics ◽  
2018 ◽  
Vol 5 (12) ◽  
pp. 5047-5054 ◽  
Author(s):  
Etienne Lorchat ◽  
Stefano Azzini ◽  
Thibault Chervy ◽  
Takashi Taniguchi ◽  
Kenji Watanabe ◽  
...  
Keyword(s):  
Transition Metal ◽  
Room Temperature ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenide ◽  
Van Der Waals Heterostructures ◽  
Valley Polarization

scholarly journals Transition metal dichalcogenide metamaterials with atomic precision

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Battulga Munkhbat ◽  
Andrew B. Yankovich ◽  
Denis G. Baranov ◽  
Ruggero Verre ◽  
Eva Olsson ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Graphene Monolayer ◽  
Transition Metal Dichalcogenide ◽  
Two Dimensional ◽  
Precise Control ◽  
Two Dimensional Materials ◽  
Atomic Precision ◽  
Metal Dichalcogenides ◽  
The One

Abstract The ability to extract materials just a few atoms thick has led to the discoveries of graphene, monolayer transition metal dichalcogenides (TMDs), and other important two-dimensional materials. The next step in promoting the understanding and utility of flatland physics is to study the one-dimensional edges of these two-dimensional materials as well as to control the edge-plane ratio. Edges typically exhibit properties that are unique and distinctly different from those of planes and bulk. Thus, controlling the edges would allow the design of materials with combined edge-plane-bulk characteristics and tailored properties, that is, TMD metamaterials. However, the enabling technology to explore such metamaterials with high precision has not yet been developed. Here we report a facile and controllable anisotropic wet etching method that allows scalable fabrication of TMD metamaterials with atomic precision. We show that TMDs can be etched along certain crystallographic axes, such that the obtained edges are nearly atomically sharp and exclusively zigzag-terminated. This results in hexagonal nanostructures of predefined order and complexity, including few-nanometer-thin nanoribbons and nanojunctions. Thus, this method enables future studies of a broad range of TMD metamaterials through atomically precise control of the structure.

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