Search results for "graphe"
showing 10 items of 563 documents
Plenty of motion at the bottom: atomically thin liquid gold membrane
2015
The discovery of graphene some ten years ago was the first proof of a free-standing two-dimensional (2D) solid phase. Here, using quantum molecular dynamics simulations of nanoscale gold patches suspended in graphene pores, we predict the existence of an atomically thin, free-standing 2D liquid phase. The liquid phase, enabled by the exceptional planar stability of gold due to relativistic effects, demonstrates extreme fluxionality of metal nanostructures and opens possibilities for a variety of nanoscale phenomena.
Kinks and antikinks of buckled graphene: A testing ground for phi^4 field model
2017
Kinks and antikinks of the classical ${\ensuremath{\varphi}}^{4}$ field model are topological solutions connecting its two distinct ground states. Here we establish an analogy between the excitations of a long graphene nanoribbon buckled in the transverse direction and ${\ensuremath{\varphi}}^{4}$ model results. Using molecular dynamics simulations, we investigated the dynamics of a buckled graphene nanoribbon with a single kink and with a kink-antikink pair. Several features of the ${\ensuremath{\varphi}}^{4}$ model have been observed including the kink-antikink capture at low energies, kink-antikink reflection at high energies, and a bounce resonance. Our results pave the way towards the …
Coupled plasmonic graphene wires: theoretical study including complex frequencies and field distributions of bright and dark surface plasmons
2020
Theoretical research on localized surface plasmons (LSPs) supported by a structure formed by two parallel dielectric wires with a circular cross section wrapped with a graphene sheet has an impact in the practical realm. Here, LSPs are represented in the form of an infinite series of cylindrical multipole partial waves linked to each of the graphene wires. To obtain the kinematics (complex eigenfrequencies) and dynamic characteristics (field distributions) of the LSPs, we consider the analytic extension to the complex plane of the solution to the boundary value problem. The lower frequency LSP group is formed by four branches, two of them corresponding to bright modes and the others to dark…
Understanding and controlling N-dimensional quantum walks via dispersion relations: application to the two-dimensional and three-dimensional Grover w…
2013
The discrete quantum walk in N dimensions is analyzed from the perspective of its dispersion relations. This allows understanding known properties, as well as designing new ones when spatially extended initial conditions are considered. This is done by deriving wave equations in the continuum, which are generically of the Schrodinger type, and allows devising interesting behavior, such as ballistic propagation without deformation, or the generation of almost flat probability distributions, which is corroborated numerically. There are however special points where the energy surfaces display intersections and, near them, the dynamics is entirely different. Applications to the two- and three-d…
The amazing graphene: an educational bridge connecting different Physics concepts
2017
The purpose of this work is to present a learning workshop covering various physics concepts aimed at strengthening physics/engineering student understanding about the remarkable properties of two dimensional materials, graphene in particular. At the basis of this learning experience is the idea of blending and interconnecting separate pieces of knowledge already acquired by undergraduates in different courses and to help them visualize and link the concepts lying beyond separate chunks of information or equations. Graphene represents an appropriate unifying framework to achieve this task in view of its monatomic structure and various exotic processes peculiar to this and some other two dim…
A 5E-Based Learning Workshop on Various Aspects of the Hall Effect
2019
Learning activities in constructivist environments are characterized by active engagement, inquiry, problem solving, and collaboration with peers. The 5E learning cycle is a student-centered instructional model for constructivism, where the students perform five phases of instruction: Engagement, Exploration, Explanation, Elaboration, Evaluation. The purpose of this contribution is to present a 5E-based learning path of advanced physics aimed at strengthening Physics/Engineering student understanding about the quantum Hall effect, a phenomenon observed at low temperatures in a two-dimensional electron gas subject to a strong perpendicular magnetic field. The quantum Hall effect, a rare exam…
Elementary Polarizability of Sc/Fullerene/Graphene Aggregates and Di/Graphene–Cation Interactions
2014
Elementary Polarizability of Sc/Fullerene/Graphene Aggregates and Di/Graphene–Cation Interactions Interacting induced-dipoles polarization in code POLAR allows molecular polarizability, which is tested with Scn/Cn [fullerene/ graphene (GR)]/Scn@Cm clusters. Polarizability sees clusters of unlike sizes, parting isomers. Bulk limit is estimated from Clausius– Mossotti relation. Clusters are more polarizable than the bulk. Theory yielded this for small Sin/Gen/GanAsm; however, experiment, reversely for larger Sin/GanAsm/GenTem. Smaller clusters need not act like middle: surface dangling bonds cause small-clusters polarizability that resembles metallic. Code AMYR models GR(2)– Mz+. A 24-atom pl…
Development and characterization of a Drop-on-Demand inkjet printing system for nuclear target fabrication
2017
Abstract A novel target preparation method based on Drop-on-Demand (DoD) inkjet printing has been developed. Conventional preparation methods like the electrochemical method “Molecular Plating” or the “Polymer-Assisted Deposition Method” are often limited, e.g., concerning the dimensions and geometries of depositions or by the requirement for electrically conducting substrates. Here, we report on the development of a new technique, which overcomes such limits by using a commercially available DoD dispenser. A variety of solutions with volumes down to 5 nL can be dispensed onto every manageable substrate. The dispensed volumes were determined with a radioactive tracer and the deposits of eva…
Rashba spin-orbit-interaction-based quantum pump in graphene
2012
We present a proposal for an adiabatic quantum pump based on a graphene monolayer patterned by electrostatic gates and operated in the low-energy Dirac regime. The setup under investigation works in the presence of inhomogeneous spin-orbit interactions of intrinsic- and Rashba-type and allows to generate spin polarized coherent current. A local spin polarized current is induced by the pumping mechanism assisted by the spin-double refraction phenomenon.
Topological Signatures in the Electronic Structure of Graphene Spirals
2013
Topology is familiar mostly from mathematics, but also natural sciences have found its concepts useful. Those concepts have been used to explain several natural phenomena in biology and physics, and they are particularly relevant for the electronic structure description of topological insulators and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian constrained by space curvature, graphene spirals have topologically protected states due to tim…