scholarly journals All-optical nonreciprocity due to valley polarization pumping in transition metal dichalcogenides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sriram Guddala ◽  
Yuma Kawaguchi ◽  
Filipp Komissarenko ◽  
Svetlana Kiriushechkina ◽  
Anton Vakulenko ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Vital Role ◽  
Practical Applications ◽  
Propagation Of Light ◽  
Intervalley Scattering ◽  
All Optical ◽  
Valley Polarization ◽  
Metal Dichalcogenides ◽  
Pass Through

AbstractNonreciprocity and nonreciprocal optical devices play a vital role in modern photonic technologies by enforcing one-way propagation of light. Here, we demonstrate an all-optical approach to nonreciprocity based on valley-selective response in transition metal dichalcogenides (TMDs). This approach overcomes the limitations of magnetic materials and it does not require an external magnetic field. We provide experimental evidence of photoinduced nonreciprocity in a monolayer WS2 pumped by circularly polarized (CP) light. Nonreciprocity stems from valley-selective exciton population, giving rise to nonlinear circular dichroism controlled by CP pump fields. Our experimental results reveal a significant effect even at room temperature, despite considerable intervalley-scattering, showing promising potential for practical applications in magnetic-free nonreciprocal platforms. As an example, here we propose a device scheme to realize an optical isolator based on a pass-through silicon nitride (SiN) ring resonator integrating the optically biased TMD monolayer.

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 Dark excitons and the elusive valley polarization in transition metal dichalcogenides

2D Materials ◽  
2017 ◽  
Vol 4 (2) ◽  
pp. 025016 ◽  
Author(s):  
M Baranowski ◽  
A Surrente ◽  
D K Maude ◽  
M Ballottin ◽  
A A Mitioglu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Valley Polarization ◽  
Metal Dichalcogenides

scholarly journals Inverted valley polarization in optically excited transition metal dichalcogenides

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Gunnar Berghäuser ◽  
Ivan Bernal-Villamil ◽  
Robert Schmidt ◽  
Robert Schneider ◽  
Iris Niehues ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Dichalcogenides ◽  
Valley Polarization ◽  
Metal Dichalcogenides ◽  
Excited Transition

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 TEM investigation of MoSeC films

2008 ◽  
Vol 14 (S3) ◽  
pp. 7-10 ◽  
Author(s):  
C. Silviu Sandu ◽  
Tomas Polcar ◽  
Albano Cavaleiro
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Magnetron Sputtering ◽  
Transition Metal Dichalcogenides ◽  
Deposition Method ◽  
Practical Applications ◽  
Mechanical And Tribological Properties ◽  
Lubricating Material ◽  
Metal Dichalcogenides ◽  
Contact Pressures

Transition metal dichalcogenides (TMD) are widely used as self-lubricating material either as oil additive or directly as thin films. Magnetron sputtering is a deposition method allowing depositing such films with high density and adhesion. However, their spread use in practical applications is still hindered since their excellent sliding properties are deteriorated in the presence of humidity and under high contact pressures. MoSe2, one of the members of TMD family recently studied, has been co-sputtered with carbon in order to improve the mechanical and tribological properties when compared to pure MoSe2 films.

scholarly journals Computational Study of the Curvature-Promoted Anchoring of Transition Metals for Water Splitting

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3173
Author(s):  
Weiwei Liu ◽  
Youchao Kong ◽  
Bo Wang ◽  
Xiaoshuang Li ◽  
Pengfei Liu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Water Splitting ◽  
Computational Study ◽  
Transition Metal Dichalcogenides ◽  
Single Atom ◽  
Potential Candidate ◽  
Practical Applications ◽  
Small Areas ◽  
Transition Metal Atoms ◽  
Metal Dichalcogenides

Generating clean and sustainable hydrogen from water splitting processes represent a practical alternative to solve the energy crisis. Ultrathin two-dimensional materials exhibit attractive properties as catalysts for hydrogen production owing to their large surface-to-volume ratios and effective chemisorption sites. However, the catalytically inactive surfaces of the transition metal dichalcogenides (TMD) possess merely small areas of active chemical sites on the edge, thus decreasing their possibilities for practical applications. Here, we propose a new class of out-of-plane deformed TMD (cTMD) monolayer to anchor transition metal atoms for the activation of the inert surface. The calculated adsorption energy of metals (e.g., Pt) on curved MoS2 (cMoS2) can be greatly decreased by 72% via adding external compressions, compared to the basal plane. The enlarged diffusion barrier energy indicates that cMoS2 with an enhanced fixation of metals could be a potential candidate as a single atom catalyst (SAC). We made a well-rounded assessment of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which are two key processes in water splitting. The optimized Gibbs free energy of 0.02 for HER and low overpotential of 0.40 V for OER can be achieved when the proper compression and supported metals are selected. Our computational results provide inspiration and guidance towards the experimental design of TMD-based SACs.

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