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-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 Strong light-matter coupling in topological metasurfaces integrated with transition metal dichalcogenides

2021 ◽  
Vol 2015 (1) ◽  
pp. 012142
Author(s):  
Ivan Sinev ◽  
Mengyao Li ◽  
Fedor Benimetskiy ◽  
Tatiana Ivanova ◽  
Svetlana Kiriushechkina ◽  
...  
Keyword(s):  
Transition Metal ◽  
Topological Charge ◽  
Transition Metal Dichalcogenides ◽  
Strong Coupling Regime ◽  
Strong Light ◽  
Matter Coupling ◽  
Spin Polarized ◽  
Exciton Polaritons ◽  
Metal Dichalcogenides ◽  
Quantum Phenomena

Abstract Strong light-matter interactions enable unique nonlinear and quantum phenomena at moderate light intensities. Within the last years, polaritonic metasurfaces emerged as a viable candidate for realization of such regimes. In particular, planar photonic structures integrated with 2D excitonic materials, such as transition metal dichalcogenides (TMD), can support exciton polaritons – half-light half-matter quasiparticles. Here, we explore topological exciton polaritons which are formed in a suitably engineered all-dielectric topological photonic metasurface coupled to TMD monolayers. We experimentally demonstrate the transition of topological charge from photonic to polaritonic bands with the onset of strong coupling regime and confirm the presence of one-way spin-polarized edge topological polaritons. The proposed system constitutes a promising platform for photonic/solid-state interfaces for valleytronics and spintronics.

scholarly journals Second-harmonic generation enhancement in monolayer transition-metal dichalcogenides by using an epsilon-near-zero substrate

2021 ◽  
Vol 3 (1) ◽  
pp. 272-278
Author(s):  
Pilar G. Vianna ◽  
Aline dos S. Almeida ◽  
Rodrigo M. Gerosa ◽  
Dario A. Bahamon ◽  
Christiano J. S. de Matos
Keyword(s):  
Dielectric Constant ◽  
Transition Metal ◽  
Harmonic Generation ◽  
Nonlinear Effect ◽  
Second Harmonic ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide ◽  
Metal Dichalcogenides ◽  
Epsilon Near Zero

The scheme illustrates a monolayer transition-metal dichalcogenide on an epsilon-near-zero substrate. The substrate near-zero dielectric constant is used as the enhancement mechanism to maximize the SHG nonlinear effect on monolayer 2D materials.

Size-dependent phase stability in transition metal dichalcogenide nanoparticles controlled by metal substrates

Nanoscale ◽  
2021 ◽  
Author(s):  
Albert Bruix ◽  
Jeppe Vang Lauritsen ◽  
Bjork Hammer
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Phase Stability ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide ◽  
Metal Substrates ◽  
Size Dependent ◽  
Metal Dichalcogenides

Nanomaterials based on MoS2 and related transition metal dichalcogenides are remarkably versatile; MoS2 nanoparticles are proven catalysts for processes such as hydrodesulphurization and the hydrogen evolution reaction, and transition metal...

Self-Hybridized Exciton-Polaritons in Multilayers of Transition Metal Dichalcogenides for Efficient Light Absorption

ACS Photonics ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Battulga Munkhbat ◽  
Denis G. Baranov ◽  
Michael Stührenberg ◽  
Martin Wersäll ◽  
Ankit Bisht ◽  
...  
Keyword(s):  
Transition Metal ◽  
Light Absorption ◽  
Transition Metal Dichalcogenides ◽  
Exciton Polaritons ◽  
Metal Dichalcogenides

scholarly journals Exciton g-factors in monolayer and bilayer WSe2 from experiment and theory

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan Förste ◽  
Nikita V. Tepliakov ◽  
Stanislav Yu. Kruchinin ◽  
Jessica Lindlau ◽  
Victor Funk ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Transition Metal Dichalcogenide ◽  
Layer Transition ◽  
General Terms ◽  
Indirect Excitons ◽  
Metal Dichalcogenides ◽  
Experimental Findings ◽  
Experimental And Theoretical Studies

Abstract The optical properties of monolayer and bilayer transition metal dichalcogenide semiconductors are governed by excitons in different spin and valley configurations, providing versatile aspects for van der Waals heterostructures and devices. Here, we present experimental and theoretical studies of exciton energy splittings in external magnetic field in neutral and charged WSe2 monolayer and bilayer crystals embedded in a field effect device for active doping control. We develop theoretical methods to calculate the exciton g-factors from first principles for all possible spin-valley configurations of excitons in monolayer and bilayer WSe2 including valley-indirect excitons. Our theoretical and experimental findings shed light on some of the characteristic photoluminescence peaks observed for monolayer and bilayer WSe2. In more general terms, the theoretical aspects of our work provide additional means for the characterization of single and few-layer transition metal dichalcogenides, as well as their heterostructures, in the presence of external magnetic fields.

scholarly journals Exfoliated transition metal dichalcogenide nanosheets for supercapacitor and sodium ion battery applications

2019 ◽  
Vol 6 (8) ◽  
pp. 190437 ◽  
Author(s):  
Santanu Mukherjee ◽  
Jonathan Turnley ◽  
Elisabeth Mansfield ◽  
Jason Holm ◽  
Davi Soares ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ion ◽  
Coulombic Efficiency ◽  
Transition Metal Dichalcogenides ◽  
Sodium Ion ◽  
Transition Metal Dichalcogenide ◽  
Composite Electrodes ◽  
Metal Dichalcogenides ◽  
Storage Technologies ◽  
Supercapacitor Applications

Growing concerns regarding the safety, flammability and hazards posed by Li-ion systems have led to research on alternative rechargeable metal-ion electrochemical storage technologies. Among the most notable of these are Na-ion supercapacitors and batteries, motivated, in part, by the similar electrochemistry of Li and Na ions. However, sodium ion batteries (SIBs) come with their own set of issues, especially the large size of the Na + ion, its relatively sluggish kinetics and low energy densities. This makes the development of novel materials and appropriate electrode architecture of absolute significance. Transition metal dichalcogenides (TMDs) have attracted a lot of attention in this regard due to their relative ease of exfoliation, diverse morphologies and architectures with superior electronic properties. Here, we study the electrochemical performance of Mo-based two-dimensional (2D) layered TMDs (e.g. MoS 2 , MoSe 2 and MoTe 2 ), exfoliated in a superacid, for battery and supercapacitor applications. The exfoliated TMD flakes were interfaced with reduced graphene oxide (rGO) to be used as composite electrodes. Electron microscopy, elemental mapping and Raman spectra were used to analyse the exfoliated material and confirm the formation of 2D TMD/rGO layer morphology. For supercapacitor applications in aqueous electrolyte, the sulfide-based TMD (MoS 2 ) exhibited the best performance, providing an areal capacitance of 60.25 mF cm −2 . For SIB applications, TMD electrodes exhibited significantly higher charge capacities than the neat rGO electrode. The initial desodiation capacities for the composite electrodes are 468.84 mAh g −1 (1687.82 C g −1 ), 399.10 mAh g −1 (1436.76 C g −1 ) and 387.36 mAh g −1 (1394.49 C g −1 ) for MoS 2 , MoSe 2 and MoTe 2 , respectively. Also, the MoS 2 and MoSe 2 composite electrodes provided a coulombic efficiency of near 100 % after a few initial cycles.

scholarly journals Composition-induced type I and direct bandgap transition metal dichalcogenides alloy vertical heterojunctions

Nanoscale ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 201-209 ◽  
Author(s):  
Songsong Zhou ◽  
Jinliang Ning ◽  
Jianwei Sun ◽  
David J. Srolovitz
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Type I ◽  
Transition Metal Dichalcogenide ◽  
Direct Bandgap ◽  
Metal Dichalcogenides

Using alloying and/or twisting between layers to achieve the type I direct bandgaps vertical heterojunction in transition metal dichalcogenide family of MX2 (M = {Mo, W}, X = {S, Se}).

Recent advances in the field of transition metal dichalcogenides for biomedical applications

Nanoscale ◽  
2018 ◽  
Vol 10 (35) ◽  
pp. 16365-16397 ◽  
Author(s):  
Vipul Agarwal ◽  
Kaushik Chatterjee
Keyword(s):  
Transition Metal ◽  
Biomedical Applications ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Solid Lubrication ◽  
Transition Metal Dichalcogenide ◽  
Unique Combination ◽  
Energy Materials ◽  
Wide Range ◽  
Metal Dichalcogenides

Nanosheets of transition metal dichalcogenide (TMDs), the graphene-like two-dimensional (2D) materials, exhibit a unique combination of properties and have attracted enormous research interest for a wide range of applications including catalysis, functional electronics, solid lubrication, photovoltaics, energy materials and most recently in biomedical applications.

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