Edge effect of strained bilayer nanofilms for tunable multistability and actuation.
Ontology highlight
ABSTRACT:
SUBMITTER: Hu N
PROVIDER: S-EPMC5334438 | biostudies-literature | 2017 Mar
REPOSITORIES: biostudies-literature
Publications
Edge effect of strained bilayer nanofilms for tunable multistability and actuation.
Hu N N Han X X Huang S S Grover H M HM Yu X X Zhang L N LN Trase I I Zhang J X J JX Zhang L L Dong L X LX Chen Z Z
Nanoscale 20170301 9
We employed both theoretical and computational models supported by experiments to study the multistable behavior of an edge-effect driven Si/Cr micro-claw. Our study showed that individual micro-claws demonstrate either monostability or bistability as the magnitude of the edge effect is varied. ...[more]
Similar Datasets
Project description:Metamaterials are artificial materials that derive their unusual properties from their periodic architecture. Some metamaterials can deform their internal structure to switch between different properties. However, the precise control of these deformations remains a challenge, as these structures often exhibit non-linear mechanical behavior. We introduce a computational and experimental strategy to explore the folding behavior of a range of 3D prismatic building blocks that exhibit controllable multifunctionality. By applying local actuation patterns, we are able to explore and visualize their complex mechanical behavior. We find a vast and discrete set of mechanically stable configurations, that arise from local minima in their elastic energy. Additionally these building blocks can be assembled into metamaterials that exhibit similar behavior. The mechanical principles on which the multistable behavior is based are scale-independent, making our designs candidates for e.g., reconfigurable acoustic wave guides, microelectronic mechanical systems and energy storage systems.
| S-EPMC6898700 | biostudies-literature
Project description:Silicon nitride stress capping layer is an industry proven technique for increasing electron mobility and drive currents in n-channel silicon MOSFETs. Herein, the strain induced by silicon nitride is firstly characterized through the changes in photoluminescence and Raman spectra of a bare bilayer MoS2 (Molybdenum disulfide). To make an analogy of the strain-gated silicon MOSFET, strain is exerted to a bilayer MoS2 field effect transistor (FET) through deposition of a silicon nitride stress liner that warps both the gate and the source-drain area. Helium plasma etched MoS2 layers for edge contacts. Current on/off ratio and other performance metrics are measured and compared as the FETs evolve from back-gated, to top-gated and finally, to strain-gated configurations. While the indirect band gap of bilayer MoS2 at 0% strain is 1.25?eV, the band gap decreases as the tensile strain increases on an average of ~100?meV per 1% tensile strain, and the decrease in band gap is mainly due to lowering the conduction band at K point. Comparing top- and strain-gated structures, we find a 58% increase in electron mobility and 46% increase in on-current magnitude, signalling a benign effect of tensile strain on the carrier transport properties of MoS2.
| S-EPMC5301248 | biostudies-literature
Project description:Gunn (or Gunn-Hilsum) Effect and its associated negative differential resistivity (NDR) emanates from transfer of electrons between two different energy subbands. This effect was observed in semiconductors like GaAs which has a direct bandgap of very low effective mass and an indirect subband of high effective mass which lies ~300?meV above the former. In contrast to GaAs, bulk silicon has a very high energy spacing (~1?eV) which renders the initiation of transfer-induced NDR unobservable. Using Density Functional Theory (DFT), semi-empirical 10 orbital (sp3d5s*) Tight Binding and Ensemble Monte Carlo (EMC) methods we show for the first time that (a) Gunn Effect can be induced in silicon nanowires (SiNW) with diameters of 3.1?nm under +3% strain and an electric field of 5000?V/cm, (b) the onset of NDR in the I-V characteristics is reversibly adjustable by strain and (c) strain modulates the resistivity by a factor 2.3 for SiNWs of normal I-V characteristics i.e. those without NDR. These observations are promising for applications of SiNWs in electromechanical sensors and adjustable microwave oscillators. It is noteworthy that the observed NDC is different in principle from Esaki-Diode and Resonant Tunneling Diodes (RTD) in which NDR originates from tunneling effect.
| S-EPMC5908846 | biostudies-other
Project description:A helical type edge state, which is generally supported only on graphene with zigzag boundaries, is found to also appear in armchair graphene nanoribbons in the presence of intrinsic spin-orbit coupling and a suitable strain. At a critical strain, there appears a quantum phase transition from a quantum spin Hall state to a trivial insulator state. Further investigation shows that the armchair graphene nanoribbons with intrinsic spin-orbit coupling, Rashba spin-orbit coupling, effective exchange fields and strains also support helical-like edge states with a unique spin texture. In such armchair graphene nanoribbons, the spin directions of the counterpropogating edge states on the same boundary are always opposite to each other, while is not conserved and the spins are canted away from the -direction due to the Rashba spin-orbit coupling, which is different from the case of the zigzag graphene nanoribbons. Moreover, the edge-state energy gap is smaller than that in zigzag graphene nanoribbons, even absent in certain cases.
| S-EPMC5562773 | biostudies-other
Project description:We experimentally demonstrate tunable guided resonance in twisted bilayer photonic crystals. Both the numerically and the experimentally obtained transmission spectra feature resonances with frequencies strongly dependent on the twist angle, as well as resonances with frequencies that are largely independent of the twist angle. These resonant features can be well understood with a simple analytic theory based on band folding. Our work illustrates the rich tunable resonance physics in twisted bilayer systems.
| S-EPMC9710865 | biostudies-literature
Project description:There are numerous works that report wirelessly controlling the locomotion of soft robots through a single actuation method of light or magnetism. However, coupling multiple driving modes to improve the mobility of robots is still in its infancy. Here, we present a soft multi-legged millirobot that can move, climb a slope, swim and detect a signal by near-infrared irradiation (NIR) light or magnetic field dual actuation. Due to the design of the feet structure, our soft millirobot incorporates the advantages of a single actuation mode of light or magnetism. Furthermore, it can execute a compulsory exercise to sense a signal and analyze the ambience fluctuation in a narrow place. This work provides a novel alternative for soft robots to achieve multimode actuation and signal sensing.
| S-EPMC7998303 | biostudies-literature
Project description:We report the realization of a synthetic magnetic field for photons and polaritons in a honeycomb lattice of coupled semiconductor micropillars. A strong synthetic field is induced in both the s and p orbital bands by engineering a uniaxial hopping gradient in the lattice, giving rise to the formation of Landau levels at the Dirac points. We provide direct evidence of the sublattice symmetry breaking of the lowest-order Landau level wavefunction, a distinctive feature of synthetic magnetic fields. Our realization implements helical edge states in the gap between n = 0 and n = ±1 Landau levels, experimentally demonstrating a novel way of engineering propagating edge states in photonic lattices. In light of recent advances in the enhancement of polariton-polariton nonlinearities, the Landau levels reported here are promising for the study of the interplay between pseudomagnetism and interactions in a photonic system.
| S-EPMC7438334 | biostudies-literature
Project description:Polymer-based nanodiscs are valuable tools in biomedical research that can offer a detergent-free solubilization of membrane proteins maintaining their native lipid environment. Herein, we introduce a novel ca. 1.6?kDa SMA-based polymer with styrene:maleic acid moieties that can form nanodiscs containing a planar lipid bilayer which are useful to reconstitute membrane proteins for structural and functional studies. The physicochemical properties and the mechanism of formation of polymer-based nanodiscs are characterized by light scattering, NMR, FT-IR, and TEM. A remarkable feature is that nanodiscs of different sizes, from nanometer to sub-micrometer diameter, can be produced by varying the lipid-to-polymer ratio. The small-size nanodiscs (up to ca. 30?nm diameter) can be used for solution NMR spectroscopy studies whereas the magnetic-alignment of macro-nanodiscs (diameter of > ca. 40?nm) can be exploited for solid-state NMR studies on membrane proteins.
| S-EPMC5600881 | biostudies-literature
Project description:The ability to precisely control moiré patterns in two-dimensional materials has enabled the realization of unprecedented physical phenomena including Mott insulators, unconventional superconductivity, and quantum emission. Along with the twist angle, the application of independent strain in each layer of stacked two-dimensional materials-termed heterostrain-has become a powerful means to manipulate the moiré potential landscapes. Recent experimental studies have demonstrated the possibility of continuously tuning the twist angle and the resulting physical properties. However, the dynamic control of heterostrain that allows the on-demand manipulation of moiré superlattices has yet to be experimentally realized. Here, by harnessing the weak interlayer van der Waals bonding in twisted bilayer graphene devices, we demonstrate the realization of dynamically tunable heterostrain of up to 1.3%. Polarization-resolved Raman spectroscopy confirmed the existence of substantial heterostrain by presenting triple G peaks arising from the independently strained graphene layers. Theoretical calculations revealed that the distorted moiré patterns via heterostrain can significantly alter the electronic structure of twisted bilayer graphene, allowing the emergence of multiple absorption peaks ranging from near-infrared to visible spectral ranges. Our experimental demonstration presents a new degree of freedom towards the dynamic modulation of moiré superlattices, holding the promise to unveil unprecedented physics and applications of stacked two-dimensional materials.
| S-EPMC8560801 | biostudies-literature
Project description:The lack of a bandgap makes bulk graphene unsuitable for room temperature transistors with a sufficient on/off current ratio. Lateral constriction of charge carriers in graphene nanostructures or vertical inversion symmetry breaking in bilayer graphene are two potential strategies to mitigate this challenge, but each alone is insufficient to consistently achieve a large enough on/off ratio (e.g. > 1000) for typical logic applications. Herein we report the combination of lateral carrier constriction and vertical inversion symmetry breaking in bilayer graphene nanoribbons (GNRs) to tune their transport gaps and improve the on/off ratio. Our studies demonstrate that the on/off current ratio of bilayer GNRs can be systematically increased upon applying a vertical electric field, to achieve a largest on/off current ratio over 3000 at room temperature.
| S-EPMC3570781 | biostudies-other