Kevin T. Chan

Multiply folded graphene

The folding of paper, hide, and woven fabric has been used for millennia to achieve enhanced articulation, curvature, and visual appeal for intrinsically flat, two-dimensional materials. For graphene, an ideal twodimensional material, folding may transform it to complex shapes with new and distinct properties. Here, we present experimental results that folded structures in graphene, termed grafold, exist, and their formations can be controlled by introducing anisotropic surface curvature during graphene synthesis or transfer processes. Using pseudopotential-density-functional-theory calculations, we also show that double folding modifies the electronic band structure of graphene. Furthermore, we demonstrate the intercalation of C60 into the grafolds. Intercalation or functionalization of the chemically reactive folds further expands grafold’s mechanical, chemical, optical, and electronic diversity.

Gate-controlled ionization and screening of cobalt adatoms on a graphene surface

By varying the voltage on an isolated gate electrode beneath a graphene sheet, the ionization state of cobalt atoms on its surface can be controlled. This enables the electronic structure of individual ionized atoms, and the resulting cloud of screening electrons that form around them, to be obtained with a scanning tunnelling microscope.

COMPASS: Computer oriented materials, processes, and apparatus selection system

Abstract Todays competitive manufacturing environment requires a shortened product development time. Although great emphasis has been placed on concurrent engineering, it is still a challenge for engineers to bridge the gap between design and manufacturing. This paper proposes a new approach to an emerging concept, Meta Planning, which brings manufacturing issues upstream by generating timely and appropriate feedback to design engineers. While a product or feature is being designed, all feasible downstream manufacturing processes can be compared. A meta planner can be integrated into existing CAD/CAPP/CAM systems to automate high-level process planning such that heterogeneous processes can be organized into a coherent plan. COMPASS (Computer Oriented Materials, Processes, and Apparatus Selection System), developed as a meta planner, has the basic framework to provide essential information regarding production cost, cycle time, and product quality for all of the candidate processes. It is a tool that helps design engineers identify potential manufacturing problems in the earlier stages of product development. Three different hole-making process models are implemented in COMPASS to illustrate the mechanism that analyzes and compares different manufacturing processes. Close interaction between design parameters and manufacturing performance for selected processes is demonstrated through a detailed case study involving a single feature.

Ytterbium-driven strong enhancement of electron-phonon coupling in graphene

We present a high-resolution angle-resolved photoemission spectroscopy study in conjunction with first-principles calculations to investigate how the interaction of electrons with phonons in graphene is modified by the presence of Yb. We find that the charges transferred from Yb to the graphene layer hybridize with the graphene

First-principles study of metal adatom adsorption on graphene

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Gated adatoms on graphene studied with first-principles calculations

bands, leading to a strong enhancement of the electron-phonon interaction. Specifically, the electron-phonon coupling constant is increased by as much as a factor of 10 upon the introduction of Yb with respect to as-grown graphene (

Pressure dependence of superconductivity in simple cubic phosphorus

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Possibility of transforming the electronic structure of one species of graphene adatoms into that of another by application of gate voltage: First-principles calculations

). The observed coupling constant constitutes the highest value ever measured for graphene and suggests that the hybridization between graphene and the adatoms might be a critical parameter in realizing superconducting graphene.