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Twisted van der Waals heterostructures provide a new platform for studying strongly correlated quantum phases. The interlayer coupling in these heterostructures is sensitive to the twist angle (θ) and key to controllably tuning several interesting properties. Here, we demonstrate the systematic evolution of the interlayer coupling strength with twist angle in bilayer MoS using a combination of Raman spectroscopy and classical simulations. At zero doping, we observe a monotonic increase in the separation between the A and E mode frequencies as θ decreases from 10°→ 1°, and the separation approaches that of a bilayer at small twist angles. Furthermore, using doping dependent Raman spectroscopy, we reveal the θ dependent softening and broadening of the A mode, whereas the E mode remains unaffected. Using first principles based simulations, we demonstrate large (weak) electron-phonon coupling for the A (E) mode, which explains the experimentally observed trends. Our study provides a non-destructive way to characterize the twist angle and the interlayer coupling and establishes the manipulation of phonons in twisted bilayer MoS (twistnonics).
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http://dx.doi.org/10.1039/c9nr09897f | DOI Listing |
J Am Chem Soc
September 2025
Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States.
Two-dimensional (2D) materials offer a valuable platform for manipulating and studying chemical reactions at the atomic level, owing to the ease of controlling their microscopic structure at the nanometer scale. While extensive research has been conducted on the structure-dependent chemical activity of 2D materials, the influence of structural transformation during the reaction has remained largely unexplored. In this work, we report the layer-dependent chemical reactivity of MoS during a nitridation atomic substitution reaction and attribute it to the rearrangement of Mo atoms.
View Article and Find Full Text PDFACS Nano
September 2025
Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.
Integration of ultrathin, high-quality gate insulators is critical to the success of two-dimensional (2D) semiconductor transistors in next-generation nanoelectronics. Here, we investigate the impact of atomic layer deposition (ALD) precursor choice on the nucleation and growth of insulators on monolayer MoS. Surveying a series of aluminum (AlO) precursors, we observe that increasing the length of the ligands reduces the nucleation delay of alumina on monolayer MoS, a phenomenon that we attribute to improved van der Waals dispersion interactions with the 2D material.
View Article and Find Full Text PDFNanoscale
September 2025
College of Materials Science and Engineering, Sichuan University, Chengdu 610065, China.
With the progress of study, MoS has been proven to show excellent properties in electronics and optoelectronics, which promotes the fabrication of future novel integrated circuits and photodetectors. However, highly uniform wafer-scale growth is still in its early stage, especially regarding how to control the precursor and its distribution. Herein, we propose a new method, spraying the Mo precursor, which is proven to fabricate highly uniform 2-inch monolayer MoS wafers.
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September 2025
Insitut für Physik and Center for the Science of Materials Berlin, Humboldt-Universität zu Berlin, Berlin 12489, Germany.
Electric gating in atomically thin field-effect devices based on transition-metal dichalcogenides has recently been employed to manipulate their excitonic states, even producing exotic phases of matter, such as an excitonic insulator or Bose-Einstein condensate. Here, we mimic the electric gating effect of a bilayer-MoS on graphite by charge transfer induced by the adsorption of molecular p- and n-type dopants. The electric fields produced are evaluated from the electronic energy-level realignment and Stark splitting determined by X-ray and UV photoelectron spectroscopy measurements and compare very well with literature values obtained by optical spectroscopy for similar systems.
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September 2025
Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
As a versatile platform for exploring exotic quantum phases, moiré superlattices, ranging from twisted graphene to twisted transition metal dichalcogenides, have been intensively studied. In this work, based on exact diagonalization and Hartree-Fock mean-field calculations, the interaction-driven topological phases are investigated in hole-doped twisted bilayer MoS at the high filling factor = 3. Besides the nematic insulator and quantum anomalous Hall phases, the topological Wigner molecule crystal (TWMC) phase is found in the phase diagram.
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