We report the observation of an electric field in twisted-bilayer molybdenum disulfide (MoS) and elucidate its correlation with local polar domains using four-dimensional scanning transmission electron microscopy (4D-STEM) and first-principles calculations. We reveal the emergence of in-plane topological vortices within the periodic moiré patterns for both commensurate structures at small twist angles and the incommensurate quasicrystal structure that occurs at a 30° twist. The large-angle twist leads to mosaic chiral vortex patterns with tunable characteristics. A twisted quasicrystal bilayer, characterized by its 12-fold rotational symmetry, hosts complex vortex patterns and can be manipulated by picometer-scale interlayer displacement. Our findings highlight that twisting 2D bilayers is a versatile strategy for tailoring local electric polar vortices.
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http://dx.doi.org/10.1126/science.adp7099 | DOI Listing |
Micron
December 2024
Department of Materials Science and Engineering, Stanford University, Stanford 94305, USA. Electronic address:
Atomic scale, scanning transmission electron microscopy (STEM) analysis of the moiré structures in twisted epitaxial gold nanodiscs encapsulated in twisted bilayer molybdenum disulfide is presented. High angle annular dark field STEM imaging reveals that the period of the moiré patterns between gold and molybdenum disulfide varies with different twist angles of the bilayer molybdenum disulfide, ranging from 1.80 nm (epitaxial alignment of gold) to 1.
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October 2024
Department of Chemistry and Center of Super-Diamond & Advanced Films (COSDAF), City University of Hong Kong, Kowloon, Hong Kong, P. R. China.
Nano Lett
March 2024
Key Laboratory of Wide Band-Gap Semiconductor Technology & Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi'an 710071, China.
Two-dimensional materials are expected to play an important role in next-generation electronics and optoelectronic devices. Recently, twisted bilayer graphene and transition metal dichalcogenides have attracted significant attention due to their unique physical properties and potential applications. In this study, we describe the use of optical microscopy to collect the color space of chemical vapor deposition (CVD) of molybdenum disulfide (MoS) and the application of a semantic segmentation convolutional neural network (CNN) to accurately and rapidly identify thicknesses of MoS flakes.
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December 2023
Polaritons in reduced-dimensional materials, such as nanowire, nanoribbon and rolled nanotube, usually provide novel avenues for manipulating electromagnetic fields at the nanoscale. Here, we theoretically propose and study hyperbolic phonon polaritons (HPhPs) with rolled one-dimensional molybdenum trioxide (MoO) nanotube structure. We find that the HPhPs in rolled MoO nanotubes exhibit low propagation losses and tunable electromagnetic confinement along the rolled direction.
View Article and Find Full Text PDFACS Appl Mater Interfaces
May 2021
Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
Constructing a bilayer system with defined twist angles is an effective way to engineer the physical properties of two-dimensional (2D) materials, opening up a new research area of twistronics. How to achieve high-quality bilayer 2D materials in a controlled and mass production way is of primary importance to this emerging area. In this work, we present a strategy for the large-scale fabrication of twisted bilayer molybdenum disulfide (MoS) through photolithography patterning and folding of single-crystal monolayer MoS.
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