arXiv subjects

S. Y. Lin

Publications and source records attributed to S. Y. Lin.

6 recordsLinked to original sources

arXiv2020

Feature-rich Geometric and Electronic Properties of Carbon Nanoscrolls

How to form carbon nanoscrolls with the non-uniform curvatures is worthy of a detailed investigation. The first-principles method is suitable in studying the combined effects due to the finite-size confinement, the edge-dependent interactions, the interlayer atomic interactions, the mechanical strains, and the magnetic configurations. The complex mechanisms can induce the unusual essential properties, e.g., the optimal structures, magnetisms, band gaps and energy dispersions. To reach a stable spiral profile, the requirements on the critical nanoribbon width and overlapping length will be thoroughly explored by evaluating the $W$-dependent scrolling energies. A comparison of formation energy between armchair and zigzag nanoscrolls is useful in understanding the experimental characterizations. The spin-up and spin-down distributions near the zigzag edges are examined for their magnetic environments. This accounts for the conservation or destruction of spin degeneracy. The various curved surfaces on a relaxed nanoscroll will create the complicated multi-orbital hybridizations, so that the low-lying energy dispersions and energy gaps are expected to be very sensitive to ribbon width, especially for those of armchair systems. Finally, the planar, curved, folded, scrolled graphene nanoribbons are compared with one another to illustrate the geometry-induced diversity.

cond-mat.mes-hall↗

arXiv2019

The Simulation of the Sensitivity of the Antarctic Impulsive Transient Antenna (ANITA) to Askaryan Radiation from Cosmogenic Neutrinos Interacting in the Antarctic Ice

A Monte Carlo simulation program for the radio detection of Ultra High Energy (UHE) neutrino interactions in the Antarctic ice as viewed by the Antarctic Impulsive Transient Antenna (ANITA) is described in this article. The program, icemc, provides an input spectrum of UHE neutrinos, the parametrization of the Askaryan radiation generated by their interaction in the ice, and the propagation of the radiation through ice and air to a simulated model of the third and fourth ANITA flights. This paper provides an overview of the icemc simulation, descriptions of the physics models used and of the ANITA electronics processing chain, data/simulation comparisons to validate the predicted performance, and a summary of the impact of published results.

astro-ph.IM↗

arXiv2018

Metal-adsorbed graphene nanoribbons

The metal atoms, the alkali ones excepted, might provide the multiple outermost orbitals for the multi-orbital hybridizations with the out-of-plane $π$ bondings on the honeycomb lattice. This will dominate the fundamental properties of Al-, Ti- and Bi-adsorbed graphene nanoribbons, in which they are explored thoroughly by using the first-principles calculations. The principle focuses are the adatom-dependent binding energies, the adatom-carbon lengths, the optimal position, the maximum adatom concentrations, the free electron density transferred per adatom, the adatom-related valence and conduction bands, the various van Hove singularities in DOSs, the transition-metal-induced magnetic properties, and the significant competitions of the zigzag edge carbons and the metal/transition metal adatoms in spin configurations. The distinct chemical bondings are clearly identified from three kinds of metal adatoms under the delicate physical quantities. The important differences between Al-/Ti-/Bi- and alkali-adsorbed graphene nanoribbons will be discussed in detail, covering band structures, relation of conduction electron density and adatom concentration, spatial charge distributions, orbital-decomposed DOSs, and magnetic configurations $\&$ moments.

cond-mat.mes-hall↗

arXiv2018

Observation of an Unusual Upward-going Cosmic-ray-like Event in the Third Flight of ANITA

We report on an upward traveling, radio-detected cosmic-ray-like impulsive event with characteristics closely matching an extensive air shower. This event, observed in the third flight of the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload, is consistent with a similar event reported in a previous flight. These events may be produced by the atmospheric decay of an upward-propagating $τ$-lepton produced by a $ν_τ$ interaction, although their relatively steep arrival angles create tension with the standard model (SM) neutrino cross section. Each of the two events have $a~posteriori$ background estimates of $\lesssim 10^{-2}$ events. If these are generated by $τ$-lepton decay, then either the charged-current $ν_τ$ cross section is suppressed at EeV energies, or the events arise at moments when the peak flux of a transient neutrino source was much larger than the typical expected cosmogenic background neutrinos.

astro-ph.HE↗

arXiv2016

Substrate-induced structures of bismuth adsorption on graphene: a first principle study

The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a $\sim 50$ meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at $\sim -0.2$ eV, and a peak at $\sim -0.6$ eV, as observed in the experimental measurements of the tunneling conductance.

cond-mat.mtrl-sci↗

arXiv2000

Evidence For Heavy Hole and Light Hole Current Separation in P-Type Resonant Tunneling Diodes With Prewells

We investigate the transport of holes through $AlAs/In_{.10}Ga_{.90}As$ resonant tunneling diodes which utilize $In_xGa_{1-x}As$ prewells in the emitter with $x=0,.10,$ and $.20$. The data show an increase in peak current and bias at resonance and a concurrent increase in the peak-to-valley ratio with increasing x. We explain this enhancement in tunneling as due to confinement (or localiz- ation) of charges in the prewell and the formation of direct heavy(light) hole to heavy(light) hole conduction channels as a consequence.

cond-mat.mes-hall↗