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Topological defects are ubiquitous, they manifest in a wide variety of systems such as liquid crystals, magnets or superconductors. The recent quest for non‐abelian anyons in condensed matter physics stimulates the interest for topological defects since they can be hosted in vortices in quantum magnets or topological superconductors. In addition to these vortex defects, this study proposes to investigate edge dislocations in 2D magnets as new building blocks for topological physics since they can be described as vortices in the structural phase field. It demonstrates the existence of higher order topological dislocations within the higher order moiré pattern of the van der Waals 2D magnet CrCl3 deposited on Au(111). Surprisingly, these higher order dislocations arise from ordinary simple edge dislocations in the atomic lattice of CrCl3. This study provide a theoretical framework explaining the higher order dislocations as vortices with a winding Chern number of 2. It is expected that these original defects can stabilize some anyons either in a 2D quantum magnet or within a 2D superconductor coupled to it. [ABSTRACT FROM AUTHOR]

Despite numerous limitations, graphene characterization using scanning tunneling microscopy is an important aspect of graphene research. In the present study, an ambient, large effective field of view scanning tunneling microscope (A‐LEF‐STM) is used as a more practical extension of a standard STM for analyzing chemical vapor deposited (CVD)‐graphene: A rigid sample stage, which allows the tip to be relocated to any point over an area of 3.5 × 3.5 mm, is attached to the latter. This simple enhancement allows rough patches spanning hundreds of nanometers on any sample to be easily circumnavigated, almost always without damaging the tip. Ripples and multi‐layer regions including those with twisted bi‐layers, in a graphene sheet grown on a copper foil using CVD, are located using the augmented manoeuvrability, and imaged in high‐definition from micron to angström scales. Insights relating to the resolution with which surfaces of varying roughness can be imaged are developed using simulations and a careful analysis of the scanning process. The enhanced field of view is also utilized to verify the extent of graphene coverage over the entire sample area. The acquired images of single and multi‐layer depositions are carefully interpreted. The applicability of this end‐to‐end characterization process for other samples is also discussed. Overall, this study demonstrates the potential benefits of the A‐LEF‐STM as an eminent characterization tool, complementary to a Raman spectrometer, for CVD‐graphene and other two‐dimensional materials. [ABSTRACT FROM AUTHOR]

Here, a deterministic algorithm is proposed, that is capable of constructing a common supercell between two similar crystalline surfaces without scanning all possible cases. Using the complex plane, the 2D lattice is defined as the 2D complex vector. Then, the relationship between two surfaces becomes the eigenvector–eigenvalue relation where an operator corresponds to a transformation matrix. It is shown that this transformation matrix can be directly determined from the lattice parameters and rotation angle of the two given crystalline surfaces with O(log Nmax) time complexity, where Nmax is the maximum index of repetition matrix elements. This process is much faster than the conventional brute force approach (O(Nmax4)$O(N_{\mathrm{max}}^4)$). By implementing the method in Python code, experimental 2D heterostructures and their moiré patterns and additionally find new moiré patterns that have not yet been reported are successfully generated. According to the density functional theory (DFT) calculations, some of the new moiré patterns are expected to be as stable as experimentally‐observed moiré patterns. Taken together, it is believed that the method can be widely applied as a useful tool for designing new heterostructures with interesting properties. [ABSTRACT FROM AUTHOR]

Optical tracking of head pose via fiducial markers has been proven to enable effective correction of motion artifacts in the brain during magnetic resonance imaging but remains difficult to implement in the clinic due to lengthy calibration and set up times. Advances in deep learning for markerless head pose estimation have yet to be applied to this problem because of the sub-millimetre spatial resolution required for motion correction. In the present work, two optical tracking systems are described for the development and training of a neural network: one marker-based system (a testing platform for measuring ground truth head pose) with high tracking fidelity to act as the training labels, and one markerless deep-learning-based system using images of the markerless head as input to the network. The markerless system has the potential to overcome issues of marker occlusion, insufficient rigid attachment of the marker, lengthy calibration times, and unequal performance across degrees of freedom (DOF), all of which hamper the adoption of marker-based solutions in the clinic. Detail is provided on the development of a custom moiré-enhanced fiducial marker for use as ground truth and on the calibration procedure for both optical tracking systems. Additionally, the development of a synthetic head pose dataset is described for the proof of concept and initial pre-training of a simple convolutional neural network. Results indicate that the ground truth system has been sufficiently calibrated and can track head pose with an error of <1 mm and <1°. Tracking data of a healthy, adult participant are shown. Pre-training results show that the average root-mean-squared error across the 6 DOF is 0.13 and 0.36 (mm or degrees) on a head model included and excluded from the training dataset, respectively. Overall, this work indicates excellent feasibility of the deep-learning-based approach and will enable future work in training and testing on a real dataset in the MRI environment. [ABSTRACT FROM AUTHOR]

Abstract Two twisted bismuth bilayers, TBB, each with 120 atoms, are studied using their electron density of states and their vibrational density of states using first‐principles calculations. Metallic character at the Fermi level is found for the non‐rotated sample as well as for each sample rotated 0.5°, 1.0°, 1.5°, 2.0°, 2.5°, 3.0°, 4.0°, 5.0°, 6.0°, 7.0°, 8.0°, and 10° with respect to each other. Assuming that the superconductivity is BCS‐type and the invariance of the Cooper pairing potential, a maximum superconducting temperature TC ≈1.8 K is predicted for a magic angle of 0.5° between the two bilayers, increasing the superconducting transition temperature from the experimentally measured value of 0.53 mK for the Wyckoff structure of crystalline bismuth.

Moiré patterns caused by aliasing between the camera's sensor and the monitor can severely degrade image quality. Image demoiréing is a multi-task image restoration method that includes texture and color restoration. This paper proposes a new multibranch wavelet-based image demoiréing network (MBWDN) for moiré pattern removal. Moiré images are separated into sub-band images using wavelet decomposition, and demoiréing can be achieved using the different learning strategies of two networks: moiré removal network (MRN) and detail-enhanced moiré removal network (DMRN). MRN removes moiré patterns from low-frequency images while preserving the structure of smooth areas. DMRN simultaneously removes high-frequency moiré patterns and enhances fine details in images. Wavelet decomposition is used to replace traditional upsampling, and max pooling effectively increases the receptive field of the network without losing the spatial information. Through decomposing the moiré image into different levels using wavelet transform, the feature learning results of each branch can be fully preserved and fed into the next branch; therefore, possible distortions in the recovered image are avoided. Thanks to the separation of high- and low-frequency images during feature training, the proposed two networks achieve impressive moiré removal effects. Based on extensive experiments conducted using public datasets, the proposed method shows good demoiréing validity both quantitatively and qualitatively when compared with the state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

It is crucial to deeply understand how the interlayer interaction acts on controlling the structural and electronic properties of shifted patterns of bilayer phosphorene. A comprehensive first-principles study on the bilayer phosphorene through relative translation along different directions has revealed that there is a direct correlation between the potential energy surface and the interlayer equilibrium distance. The shorter the interlayer distance, the lower the potential energy surface. The shifted patterns with the most stable state, the metastable state, and the transition state (with energy barrier of ∼1.3 meV/atom) were found associated with the AB, the A δ, and the TS stacking configurations, respectively. The high energy barriers, on the other hand, are ∼9.3 meV/atom at the AA stacking configuration along the zigzag pathway, ∼5.3 meV/atom at the AB′ stacking configuration along the armchair pathway, and ∼11.2 meV/atom at the AA′ stacking configuration along the diagonal pathway, respectively. The character of electronic bandgap with respect to the shifting shows an anisotropic behavior (with the value of 0.69–1.22 eV). A transition from the indirect to the direct bandgap occurs under the shifting, implying a tunable bandgap by stacking engineering. Furthermore, the orbital hybridization at the interfacial region induces a redistribution of the net charge (∼0.002–0.011 e) associated with the relative shifting between layers, leading to a strong polarization with stripe-like electron depletion near the lone pairs and accumulation in the middle of the interfacial region. It is expected that such interesting findings will provide a fundamental reference to deeply understand and analyze the complex local structural and electronic properties of twisted bilayer phosphorene and will make the shifted patterns of bilayer phosphorene promising for nanoelectronics as versatile shiftronics materials. [ABSTRACT FROM AUTHOR]

In this work a bilayer moiré graphene structure with a spatial period of energy parameters change of the ten nanometers order is considered. The layer misorientation angle effect and the energy gap parameter on the current-voltage characteristic of the structure is studied numerically. The transmission coefficients calculation through the structure demonstrates the appearance of energy gaps, the magnitude of which depends on the misorientation angle of the layers. [ABSTRACT FROM AUTHOR]

this study presents a method to recover the response function of a flexible latex membrane undergoing a dynamic event by volume oscillation using Double Digital Fringe Projection to measure the profile of the surface in a sequence of frames. By applying a frequency filter to the interference pattern, a moiré pattern was obtained. Optical phase retrieval from individual frames was performed using the Isotropic Quadrature Transform Algorithm. This fringe projection technique enables full-field measurements, including edges where other techniques could not perform due to shadows generated by the tilt angle. The procedure was devised as a non-contact system to retrieve the deformation function of a flexible surface, enhancing a valuable aspect of the methodology. The results demonstrate successful recovery of the membrane response function, highlighting the relevance of the method for accurate deformation measurements using a straightforward system. These outcomes provide significant value for the development of precise measurement techniques for flexible structures in engineering applications, such as soft robotics, biomedical devices, and material science. [ABSTRACT FROM AUTHOR]

Bioresponsive hydrogels are smart materials that respond to various external stimuli and exhibit great potential as biosensors owing to their capability of real-time and label-free detection. Here, we propose a sensing platform based on bioresponsive hydrogels, employing the concept of moiré patterns. Two sets of line patterns with different pitch sizes are prepared; a hydrogel grating whose pitch size changes according to external stimuli and a reference grating with constant pitch size. The volume changes of the hydrogel caused by external stimuli changes the pitch size of the hydrogel grating, and subsequently, the pitch sizes of the moiré patterns (moiré signal), whose values can be obtained in a real-time and label-free manner through customized moiré microscopy and signal processing. After confirming that the pH-induced swelling of hydrogel could be monitored using moiré patterns, we performed moiré pattern-based detection of specific proteins using protein-responsive hydrogel that underwent shrinking via interaction with target proteins. Brain-derived neurotrophic factor and platelet-derived growth factor were selected as the model proteins, and our proposed system successfully detected both proteins at nanomolar levels. In both cases, the pitch size change of hydrogel grating was monitored much more sensitively using moiré patterns than through direct measurements. The changes in the moiré signals caused by target proteins were detected in ex-vivo environments using a custom-made intraocular lens incorporating the hydrogel grating, demonstrating the capability of the proposed system to detect various markers in intraocular aqueous humor, when implanted in the eye.

Moiré patterns caused by aliasing between the camera’s sensor and the monitor can severely degrade image quality. Image demoiréing is a multi-task image restoration method that includes texture and color restoration. This paper proposes a new multibranch wavelet-based image demoiréing network (MBWDN) for moiré pattern removal. Moiré images are separated into sub-band images using wavelet decomposition, and demoiréing can be achieved using the different learning strategies of two networks: moiré removal network (MRN) and detail-enhanced moiré removal network (DMRN). MRN removes moiré patterns from low-frequency images while preserving the structure of smooth areas. DMRN simultaneously removes high-frequency moiré patterns and enhances fine details in images. Wavelet decomposition is used to replace traditional upsampling, and max pooling effectively increases the receptive field of the network without losing the spatial information. Through decomposing the moiré image into different levels using wavelet transform, the feature learning results of each branch can be fully preserved and fed into the next branch; therefore, possible distortions in the recovered image are avoided. Thanks to the separation of high- and low-frequency images during feature training, the proposed two networks achieve impressive moiré removal effects. Based on extensive experiments conducted using public datasets, the proposed method shows good demoiréing validity both quantitatively and qualitatively when compared with the state-of-the-art approaches.

This study presents a method to recover the response function of a flexible latex membrane undergoing a dynamic event by volume oscillation using Double Digital Fringe Projection to measure the profile of the surface in a sequence of frames. By applying a frequency filter to the interference pattern, a moiré pattern was obtained. Optical phase retrieval from individual frames was performed using the Isotropic Quadrature Transform Algorithm. This fringe projection technique enables full-field measurements, including edges where other techniques could not perform due to shadows generated by the tilt angle. The procedure was devised as a non-contact system to retrieve the deformation function of a flexible surface, enhancing a valuable aspect of the methodology. The results demonstrate successful recovery of the membrane response function, highlighting the relevance of the method for accurate deformation measurements using a straightforward system. These outcomes provide significant value for the development of precise measurement techniques for flexible structures in engineering applications, such as soft robotics, biomedical devices, and material science.

The stacking state of atomic layers critically determines the physical properties of twisted van der Waals materials. Unfortunately, precise characterization of the stacked interfaces remains a great challenge as they are buried internally. With conductive atomic force microscopy, we show that the moiré superlattice structure formed at the embedded interfaces of small-angle twisted multilayer graphene (tMLG) can noticeably regulate surface conductivity even when the twisted interfaces are 10 atomic layers beneath the surface. Assisted by molecular dynamics (MD) simulations, a theoretical model is proposed to correlate surface conductivity with the sequential stacking state of the graphene layers of tMLG. The theoretical model is then employed to extract the complex structure of a tMLG sample with crystalline defects. Probing and visualizing the internal stacking structures of twisted layered materials is essential for understanding their unique physical properties, and our work offers a powerful tool for this via simple surface conductivity mapping. [ABSTRACT FROM AUTHOR]

Interface has a significant effect on mechanical properties of graphene reinforced metal composites. Taking graphene nanosheet reinforced iron composite (Gr/Fe) as an example, the interfacial characteristics of Gr/Fe (110), (111), ( 11 2 ¯ ), and (001) interfaces have been studied using molecular dynamics (MD) simulations. Two types of interfacial bonding have been examined: physical and chemical bonding. The results show that when the graphene and iron form a physical adsorption (weak-bonded) interface, the interactive energy of the graphene and Fe (110), (111), ( 11 2 ¯ ), and (001) interface is −1.00 J/m2, −0.73 J/m2, −0.82 J/m2, and −0.81 J/m2, respectively. The lengths of the Fe-C bonding are distributed in the range of 2.20–3.00 Å without carbide formation, and no distinct patterns of atomic structure are identified. When the graphene and iron form a chemical (strong-bonded) interface, the corresponding interactive energy is −5.63 J/m2, −4.32 J/m2, −4.39 J/m2, and −4.52 J/m2, respectively. The lengths of the Fe-C bonding are mainly distributed in the ranges of 1.80–2.00 Å and 2.30–2.50 Å, which the carbides such as Fe3C and Fe7C3 are formed at the interface. Moiré patterns are observed at different-oriented interfaces, because of the lattice geometrical mismatch between graphene and different-oriented iron crystal structures. The pattern of diamond stripe is at the (110) interface, which is in good accordance with the experiment. Other patterns are the hexagonal pattern at the (111) interface, the wavy stripe pattern at the ( 11 2 ¯ ) interface, and the chain pattern at the (001) interface. These moiré patterns are formed through the competition and coordination of the three binding sites (Hollow, Bridge, and Top) of graphene with Fe atoms. [ABSTRACT FROM AUTHOR]

Mura defects, which occur during display manufacturing, degrade the quality of the display. Therefore, Mura detection is critical. When the camera is focused on the display for accurately detecting Mura defects, a moire pattern occurs in a captured image because of the frequency difference between the subpixels of the display and the color filter array of the camera. Typical image data handled with existing demoireing methods do not have Mura defects and include synthetic moire images. Therefore, we created a dataset to detect Mura defects that include real moire patterns, classified into two categories: weak and strong. We propose a new demoireing framework to remove the moire patterns in the captured image, thereby accurately detecting Mura defects. We also propose inserting ArUco markers for accurate alignment and automation, conducting multiple experiments with U-Net. Based on the captured data, the proposed U-Net, which combines a frequency loss and data augmentation, improves the performance by 6.41 dB higher for the weak moire pattern and 4.14dB higher for the strong moire pattern than state-of-the-art networks in terms of peak signal-to-noise ratio.

This work is focused on reviewing the theoretical vision of the physicist Richard Feynman about nanoscience and nanotechnology, giving continuity to his ideas in the proper context of physics laws that has led nanoscience and nanotechnology to become robust and active sciences. Some implications of nanotechnology as a general-purpose foundational technology for all economic areas are discussed. Some aspects related to interactions between the fields of mathematics, high-energy physics and condensed matter physics that have allowed the remarkable development of new quantum material platforms for nanoelectronics are also analyzed.

In this paper, we present a comprehensive study on the (4 + 1) -Fokas equation that includes new solutions and conservation laws of the equation. Specifically, for the first time, new shrunken-periodic and fascinating interactions on the bright soliton background have been investigated. Furthermore, a bright, dark, dipole soliton, tripole soliton, multipole soliton, periodic, doubly-periodic, damped-periodic, kink, lump, rogue wave, breather and their interactions have been attained and graphically illustrated. In addition, a significant interaction between four parabolic-periodic solitary waves is first detected and emphasized by harnessing 3D and contour plots. On the other hand, the latter has been compared to an experimentally-induced Moiré effect from a monitor screen camera capture. These outstanding results are achieved using the Lie symmetry approach. The multiple reduction process of the (4 + 1) -Fokas equation through the Lie algebra spanned elements, and the corresponding optimal system guarantees 23 solutions in general forms. To determine the physical meaning of the latter, an appropriate ansatz for the arbitrary functions and parameters has been proposed and listed in the corresponding tables, which leads to the various types of solitary wave solutions. Finally, the conserved vectors for the underlying equation are derived using the multiplier method. [ABSTRACT FROM AUTHOR]

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Moiré superstructures arising at twisted 2D interfaces have recently attracted the attention of the scientific community due to exotic quantum states and unique mechanical and tribological behaviors that they exhibit. Here, we predict the emergence of chiral distortions in twisted layered interfaces of finite dimensions. This phenomenon originates in intricate interplay between interfacial interactions and contact boundary constraints. A metric termed the fractional chiral area is introduced to quantify the overall chirality of the moiré superstructure and to characterize its spatial distribution. Despite the equilibrium nature of the discovered energetic and structural chirality effects, they are shown to be manifested in the twisting dynamics of layered interfaces, which demonstrates a continuous transition from stick-slip to smooth rotation with no external trigger.

The study of moiré superlattices (MSLs) has surged in recent years, as they have been found to host several emergent quantum phenomena associated with high electron correlations. In this study, we put forward a viable chemical route to the formation of moiré patterns in antimony telluride (Sb2Te3) nanoplates by leveraging screw dislocation-driven growth. These Sb2Te3 MSLs are synthesized using a scalable, one-pot, colloidal solution-liquid-solid (SLS) procedure. We report twist angles up to 0.52° (estimated using a combination of transmission electron microscope (TEM) image analysis and computer simulation). We investigate the early growth stages of Sb2Te3 spiral-type nanoplates under TEM, and we detail the growth of Sb2Te3 spiral-type nanoplates that feature a central nanopore, caused by tandem growth with nanorods. We hope that these methods will facilitate future investigation into the electronic properties of Sb2Te3 MSLs.

With the development of advanced manufacturing, superlubricity, with a friction coefficient smaller than 0.001, is highly expected at the contacting surfaces. It has been revealed that the Moiré pattern formed between two crystalline surfaces could take a crucial effect on structural superlubricity. Whereas how to tune tribological properties by manipulating the Moiré patterns is still not well studied and understood. In this work, a misfit interval statistical method (MISM) is developed to identify the geometrical characteristics of a Moiré pattern quantitatively, in which the distribution of lattice misfits can act as a good indicator to demonstrate (non-)superlubricity at the interfaces. Both the contact size (D) and the twist angle (θ) substantially affect the distribution of misfits and hence play a dominant role in affecting frictional properties. Furthermore, a parameter-free model is suggested to distinguish the regimes between non-superlubricity and superlubricity in the D- θ diagram. For the case of twisting bilayer graphene, the prediction made by this model are in good agreement with molecular dynamics (MD) simulation results. The model is generic to the other homogenous and heterogeneous interfaces, and the results in this work provide a new perspective on tuning interfacial superlubricity based on the Moiré patterns. [Display omitted] [ABSTRACT FROM AUTHOR]

Moiré superlattice has recently been found in topological insulators, which can lead to periodic modulation on the electronic structure. In this work, we report the low-temperature scanning tunneling microscopy study of Sb2Te3 films grown on graphitized 4H-SiC. We find that substrate temperature can strongly influence the rotation angles between Sb2Te3 film and graphene substrate. Three kinds of moiré patterns are observed at the first quintuple layer Sb2Te3 film under different substrate temperatures. One shows complicated patterns with a rotation angle of nearly 0° relative to the substrate, another just exhibits simple 1 × 1 structure with a rotation angle of 30°. Other rotation angle like 8.2° is observed at higher substrate temperature as well, which is relatively rare. Comparison of the dI/dV curves from Sb2Te3 films with different moiré patterns indicates that the superstructure can offer degrees of freedom in tailoring electronic structure. This work may stimulate the further study on the moiré modulation to the electronic properties of topological insulators. [ABSTRACT FROM AUTHOR]

Interface has a significant effect on mechanical properties of graphene reinforced metal composites. Taking graphene nanosheet reinforced iron composite (Gr/Fe) as an example, the interfacial characteristics of Gr/Fe (110), (111), (112¯), and (001) interfaces have been studied using molecular dynamics (MD) simulations. Two types of interfacial bonding have been examined: physical and chemical bonding. The results show that when the graphene and iron form a physical adsorption (weak-bonded) interface, the interactive energy of the graphene and Fe (110), (111), (112¯), and (001) interface is −1.00 J/m2, −0.73 J/m2, −0.82 J/m2, and −0.81 J/m2, respectively. The lengths of the Fe-C bonding are distributed in the range of 2.20–3.00 Å without carbide formation, and no distinct patterns of atomic structure are identified. When the graphene and iron form a chemical (strong-bonded) interface, the corresponding interactive energy is −5.63 J/m2, −4.32 J/m2, −4.39 J/m2, and −4.52 J/m2, respectively. The lengths of the Fe-C bonding are mainly distributed in the ranges of 1.80–2.00 Å and 2.30–2.50 Å, which the carbides such as Fe3C and Fe7C3 are formed at the interface. Moiré patterns are observed at different-oriented interfaces, because of the lattice geometrical mismatch between graphene and different-oriented iron crystal structures. The pattern of diamond stripe is at the (110) interface, which is in good accordance with the experiment. Other patterns are the hexagonal pattern at the (111) interface, the wavy stripe pattern at the (112¯) interface, and the chain pattern at the (001) interface. These moiré patterns are formed through the competition and coordination of the three binding sites (Hollow, Bridge, and Top) of graphene with Fe atoms.

Twisted van der Waals materials featuring Moiré patterns present new design possibilities and demonstrate unconventional behaviors in electrical, optical, spintronic, and superconducting properties. However, experimental exploration of thermal transport across Moiré patterns has not been as extensive, despite its critical role in nanoelectronics, thermal management, and energy technologies. Here, the first experimental study is conducted on thermal transport across twisted graphene, demonstrating a phonon polarizer concept from the rotational misalignment between stacked layers. The direct thermal and acoustic measurements, structural characterizations, and atomistic modeling, reveal a modulation up to 631% in thermal conductance with various Moiré angles, while maintaining a high acoustic transmission. By comparing experiments with density functional theory and molecular dynamics simulations, mode-dependent phonon transmissions are quantified based on the angle alignment of graphene band structures and attributed to the coupling among flexural phonon modes. The agreement confirms the dominant tuning mechanisms in adjusting phonon transmission from high-frequency thermal modes while having negligible effects on low-frequency acoustic modes near Brillouin zone center. This study offers crucial insights into the fundamental thermal transport in Moiré structures, opening avenues for the invention of quantum thermal devices and new design methodologies based on manipulations of vibrational band structures and phonon spectra., (© 2024 The Authors. Advanced Materials published by Wiley‐VCH GmbH.)

A real‐space approach for the calculation of the moiré lattice parameters for superstructures formed by a set of rotated hexagonal 2D crystals such as graphene or transition‐metal dichalcogenides is presented. Apparent moiré lattices continuously form for all rotation angles, and their lattice parameter to a good approximation follows a hyperbolical angle dependence. Moiré crystals, i.e. moiré lattices decorated with a basis, require more crucial assessment of the commensurabilities and lead to discrete solutions and a non‐continuous angle dependence of the moiré‐crystal lattice parameter. In particular, this lattice parameter critically depends on the rotation angle, and continuous variation of the angle can lead to apparently erratic changes of the lattice parameter. The solutions form a highly complex pattern, which reflects number‐theoretical relations between formation parameters of the moiré crystal. The analysis also provides insight into the special case of a 30° rotation of the constituting lattices, for which a dodecagonal quasicrystalline structure forms. [ABSTRACT FROM AUTHOR]

Recent advances in optical quantum computation set up a broad discussion on quantum supremacy and its practicability. Lack of programmability and extreme working conditions remain the challenges, calling for a programmable computation scheme. The quasi‐2D layered materials introduce new architectures for the optical neural networks (ONNs), which support various programmable computations following the on‐demand layer design. Compared with the traditional ONNs, Moiré ONNs architectures are more flexible to manufacture via layer number or twist angle control. A general Penn's model to demonstrate the mechanism inside is developed: the dielectric constant control through the layer and twisted bilayer angle dependence, respectively. Theoretically, this device can conduct demo computations ranging from boson sampling to image classification, where quantum computing shows its significant advantages. Instead of redundant 3D‐printing and lithography in traditional ONNs, the Moiré computation framework can train different tasks through programmable twists on single layers without replacing materials. [ABSTRACT FROM AUTHOR]

Here, we introduce and explore Scintillating Starbursts, a stimulus type made up of concentric star polygons that induce illusory scintillating rays or beams. We test experimentally which factors, such as contrast and number of vertices, modulate how observers experience this stimulus class. We explain how the illusion arises from the interplay of known visual processes, specifically central versus peripheral vision, and interpret the phenomenology evoked by these patterns. We discuss how Starbursts differ from similar and related visual illusions such as illusory contours, grid illusions such as the pincushion grid illusion as well as moiré patterns. [ABSTRACT FROM AUTHOR]

Generative steganography has developed recently due to its high resistance against steganalysis detection. It usually synthesizes stego images directly from secret information. In contrast to this manner, we propose a generative steganographic scheme by synthesizing Moiré patterns in this paper. Moiré patterns are widely observed in captured photos. They present various shapes, colors, and frequency ranges, which are expected to help carry secret information robustly and securely. The scheme synthesizes Moiré patterns via a Moiré pattern generator. Then a secret message is encoded in these patterns by a parallel encoder. The Moiré pattern generator employs a multi-branch structure to generate sub Moiré patterns at distinct frequencies. A discriminator is further imposed to ensure the realness of synthesized Moiré patterns. The parallel encoder spreads secret information over Moiré patterns in both frequency and spatial domain. A decoder and a steganalyzer are also included to ensure the robustness and undetectability of the information hiding. Furthermore, a two-stage training strategy is designed to accomplish both Moiré pattern generation and information hiding tasks. Experimental results demonstrate that the proposed scheme presents high undetectability against existing steganalytic tools, meanwhile, it can resist common image attacks such as AWGN and JPEG compression. [ABSTRACT FROM AUTHOR]

Moiré patterns formed by twisting and heterojunction formation have significant regulatory effects on frictional behavior, but no work has studied them through first-principles calculations combined with friction equations. In this paper, we studied the interlayer frictional properties of graphene/graphene (G/G) and graphene/hexagonal boron nitride (G/hBN) systems at different twist angles using first principles combined with the Prandtl-Tomlinson (PT), Frenkel-Kontorova (FK) and Frenkel-Kontorova-Tomlinson (FKT) models. The Moiré patterns formed by twisting and heterojunctions help to reduce the energy barrier of the system's potential energy surface (PES), thereby reducing the friction force. The stick-slip processes of the friction system are related to the energy barrier, and the reduction in the energy barrier helps transition from stick-slip to continuous sliding. The calculation results of friction models are highly consistent with reported experimental results, showing that twisting and heterojunction formation significantly reduce frictional force. Among the three models, the PT model is better in describing superlubricity during incommensurate contact. This work deepens the understanding of Moiré pattern regulation of frictional behavior and proposes a new method using a friction model combined with first principles to study frictional phenomena. [ABSTRACT FROM AUTHOR]

Semiconductor heterostructures are the fundamental platform for many important device applications such as lasers, light-emitting diodes, solar cells, and high-electron-mobility transistors. Analogous to traditional heterostructures, layered transition metal dichalcogenide heterostructures can be designed and built by assembling individual single layers into functional multilayer structures, but in principle with atomically sharp interfaces, no interdiffusion of atoms, digitally controlled layered components, and no lattice parameter constraints. Nonetheless, the optoelectronic behavior of this new type of van der Waals (vdW) semiconductor heterostructure is unknown at the single-layer limit. Specifically, it is experimentally unknown whether the optical transitions will be spatially direct or indirect in such hetero-bilayers. Here, we investigate artificial semiconductor heterostructures built from single-layer WSe2 and MoS2. We observe a large Stokes-like shift of ∼ 100 meV between the photoluminescence peak and the lowest absorption peak that is consistent with a type II band alignment having spatially direct absorption but spatially indirect emission. Notably, the photoluminescence intensity of this spatially indirect transition is strong, suggesting strong interlayer coupling of charge carriers. This coupling at the hetero-interface can be readily tuned by inserting dielectric layers into the vdW gap, consisting of hexagonal BN. Consequently, the generic nature of this interlayer coupling provides a new degree of freedom in band engineering and is expected to yield a new family of semiconductor heterostructures having tunable optoelectronic properties with customized composite layers.

In order to overcome the shortcomings of time-consuming and inefficient manual detection methods of fabric density, a fast and efficient automatic detection method of fabric density based on the digital grating is proposed. In order to realize automatic fabric density detection, the design method of the digital grating with gradual constant is described in detail on the basis of the principle of moiré pattern. The moiré pattern containing yarn density information of the fabric can be obtained by superimposing the captured fabric image and the digital grating image. After the moiré pattern is projected, the fabric density can be accurately determined by analyzing the distribution characteristics of projection curve. In the detection process, a digital grating image generated by computer is used to replace the physical grating, which not only makes the detection faster, but also make the system applicable for the fabric density detection of all kinds of specifications. Testing experiments were carried out on various fabric samples including fabrics in a plain weave and in a twill weave, the detection accuracy is more than 99.2% and the detection speed is much faster than the existing methods, which can meet the requirements of on-line detection in fabric production.

Highly-oriented pyrolytic graphite (HOPG), i.e. , the 3D stack of sp2-hybridized carbon sheets, is an attractive material thanks to its high electrical conductivity, chemical inertness, thermal stability, atomic-scale flatness, and ease of exfoliation. Despite an apparently ideal and uniform material, freshly cleaved HOPG shows domains in Kelvin probe force microscopy (KPFM) with surface potential contrast over 30 mV. We systematically investigated these domains using an integrated approach, including time-dependent KPFM and hyperspectral Raman imaging. The observed time-evolving domains are attributed to locally different hydrocarbon adsorption from the environment, driven by structural defects likely related to rotational mismatch, i.e. , twisted layers. These defects affect the interlayer coupling between topmost graphene and the underlying layers. Our hypothesis was supported by Raman spectroscopy results, showing domains with G peak shifts and 2D line shape compatible with bilayer graphene. We attribute the selective sensitivity of our Raman spectroscopy results to the top graphene layers as resonances due to van Hove singularities. Our results show that the chemical and electrical properties of HOPG are far more complex than what is generally believed due to the broken symmetry at the top surface, giving rise to graphene bilayer-like behavior. [Display omitted] • Graphite properties were thought to be set by the sp2 carbon nature and defects. • Surface potential domains appear that cannot be explained by conventional defects. • Colocalized Raman and Kelvin probe force microscopy elucidate these domains' origin. • These defects arising from graphene bilayer-like behavior impact organic adsorption. [ABSTRACT FROM AUTHOR]

Facile electrochemical graphite oxidation and functionalization with a selected array of amine moieties are carried out. The electrochemical oxidation offers the ability to preserve graphite morphological characteristics as intact adjacent surfaces yield collective van der Waals interactions. The different amine moieties are used to tether adjacent layers within graphite oxide (GO) to produce rigid framework materials. This interconnectedness is of utmost necessity for the structures to withstand cyclability in adsorptive and electronic applications. Utilizing well-ordered electrochemically-derived graphite oxide could be advantageous for the development of large-flake-size intact graphite oxide frameworks compared to inherently defective chemically-derived graphite oxide. The produced materials are extensively characterized to understand the extent, nature, and chemistry of the amine functionalization within GO domains. A balanced aromaticity in the intercalating amine species is found favorable in order to achieve a homogeneous distribution throughout graphite flakes while enhancing the interlayer spacing. Herein, notably by applying HR-TEM methods, turbostratic domains are successfully resolved in frameworks with relatively high nitrogen abundance and obtained results corroborate with 13C MAS NMR findings plausibly. The tethering mechanism induces layers rotation/twisting, giving rise to pronounced Moiré patterns. The enhanced interlayer spacing in the frameworks makes them promising candidates for storage and electronic applications. Graphite flakes are electrochemically oxidized and functionalized with different amine moieties to develop framework materials in which original Bernal stacking is partially lost in several domains as resolved by 13C NMR and HR-TEM analyses. [Display omitted] • Electrochemical oxidation of graphite flakes preserves morphological features. • Diamine grafting within GO causes emergence of minor turbostratic domains. • Turbostratic domains exhibiting Moiré patterns are resolved using Direct 13C NMR. • Grafted amine pillars hinder adsorption of nitrogen within interlayer spaces. • GO framework material is a cheap candidate to light-localizing appliances. [ABSTRACT FROM AUTHOR]

Moiré patterns at van der Waals interfaces between twisted 2D crystals give rise to distinct optoelectronic excitations, as well as, narrowly dispersive bands responsible for correlated electron phenomena. Contrasting with the conventional, mechanically stacked planar twist moirés, recent work shows twisted van der Waals interfaces spontaneously formed in nanowires of layered crystals, where Eshelby twist due to axial screw dislocations stabilizes a chiral structure with small interlayer rotation. Here, the realization of tunable twist in germanium(II) sulfide (GeS) van der Waals nanowires is reported. Tapered nanowires host continuously variable interlayer twist. Homojunctions between dislocated (chiral) and defect‐free (achiral) segments are obtained by triggering the emission of axial dislocations during growth. Measurements across such junctions, implemented here using local absorption and luminescence spectroscopy, provide a convenient tool for detecting twist effects. The results identify a versatile system for 3D twistronics, probing moiré physics, and for realizing moiré architectures without equivalent in planar systems. [ABSTRACT FROM AUTHOR]