Enhanced resistance of single-layer graphene to ion bombardment

We report that single-layer graphene on a SiO_2/Si substrate withstands ion bombardment up to ~7 times longer than expected when exposed to focused Ga^+ ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga^+ ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition

Comment on "Electron transport through correlated molecules computed using the time-independent Wigner function: Two critical tests"

The many electron correlated scattering (MECS) approach to quantum electronic transport was investigated in the linear response regime [I. Baldea and H. Koeppel, Phys. Rev. B. 78, 115315 (2008)]. The authors suggest, based on numerical calculations, that the manner in which the method imposes boundary conditions is unable to reproduce the well-known phenomena of conductance quantization. We introduce an analytical model and demonstrate that conductance quantization is correctly obtained using open system boundary conditions within the MECS approach.Comment: 18 pages, 4 figures. Physical Review B, to appea

An investigation of the basic properties of irradiated polyethylene memory materials

Properties of irradiated polyethylene memory material

Cathodoluminescence of enstatite from chondritic and achondritic meteorites and its selenological implications Technical report, 1 Sep. 1967 - 1 Jul. 1968

Cathodoluminescence of enstatite from chondritic and achondritic meteorites and selenological implication

Drug Points: Apparent interaction between warfarin and levonorgestrel used for emergency contraception

No abstract available

Fragile-to-Strong Crossover in Supercooled Liquid Ag-In-Sb-Te Studied by Ultrafast Calorimetry

Phase-change random-access memory relies on the reversible crystalline-glassy phase change in chalcogenide thin films. In this application, the speed of crystallization is critical for device performance: there is a need to combine ultrafast crystallization for switching at high temperature with high resistance to crystallization for non-volatile data retention near to room temperature. In phase-change media such as nucleation-dominated Ge2Sb2Te5, these conflicting requirements are met through the highly “fragile” nature of the temperature dependence of the viscosity of the supercooled liquid. The present study explores, using ultrafast-heating calorimetry, the equivalent temperature dependence for the growth-dominated medium Ag-In-Sb-Te. The crystallization shows (unexpectedly) Arrhenius temperature dependence over a wide intermediate temperature range. Here it is shown that this is evidence for a fragile-to-strong crossover on cooling the liquid. Such a crossover has many consequences for the interpretation and control of phase-change kinetics in chalcogenide media, helping to understand the distinction between nucleation- and growth-dominated crystallization, and offering a route to designing improved device performance.J.O., D.W.H. and A.L.G. acknowledge support from the Engineering and Physical Sciences Research Council (EPSRC, UK), D.W.H. in part through the EPSRC Centre for Innovative Manufacturing in Photonics. J.O. and A.L.G. acknowledge support from the World Premier International Research Center Initiative (WPI), MEXT, Japan. C. A. Angell, L. Battezzati, G. Dalla Fontana and M. Salinga are thanked for helpful discussions.This is the author accepted manuscript. The final version is available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/adfm.201501607/abstract

Microstructure versus Size: Mechanical Properties of Electroplated Single Crystalline Cu Nanopillars

We report results of uniaxial compression experiments on single-crystalline Cu nanopillars with nonzero initial dislocation densities produced without focused ion beam (FIB). Remarkably, we find the same power-law size-driven strengthening as FIB-fabricated face-centered cubic micropillars. TEM analysis reveals that initial dislocation density in our FIB-less pillars and those produced by FIB are on the order of 10^(14)  m^(-2) suggesting that mechanical response of nanoscale crystals is a stronger function of initial microstructure than of size regardless of fabrication method