Nanostructured graphene for spintronics

Zigzag edges of the honeycomb structure of graphene exhibit magnetic polarization making them attractive as building blocks for spintronic devices. Here, we show that devices with zigzag edged triangular antidots perform essential spintronic functionalities, such as spatial spin-splitting or spin filtering of unpolarized incoming currents. Near-perfect performance can be obtained with optimized structures. The device performance is robust against substantial disorder. The gate-voltage dependence of transverse resistance is qualitatively different for spin-polarized and spin-unpolarized devices, and can be used as a diagnostic tool. Importantly, the suggested devices are feasible within current technologies.Comment: 6 pages, 5 figures, publishe

Stability of supercooled binary liquid mixtures

Recently the supercooled Wahnstrom binary Lennard-Jones mixture was partially crystallized into ${\rm MgZn_2}$ phase crystals in lengthy Molecular Dynamics simulations. We present Molecular Dynamics simulations of a modified Kob-Andersen binary Lennard-Jones mixture that also crystallizes in lengthy simulations, here however by forming pure fcc crystals of the majority component. The two findings motivate this paper that gives a general thermodynamic and kinetic treatment of the stability of supercooled binary mixtures, emphasizing the importance of negative mixing enthalpy whenever present. The theory is used to estimate the crystallization time in a Kob-Andersen mixture from the crystallization time in a series of relared systems. At T=0.40 we estimate this time to be 5$\times 10^{7}$ time units ($\approx 1. ms$). A new binary Lennard-Jones mixture is proposed that is not prone to crystallization and faster to simulate than the two standard binary Lennard-Jones mixtures; this is obtained by removing the like-particle attractions by switching to Weeks-Chandler-Andersen type potentials, while maintaining the unlike-particle attraction

Graphene on graphene antidot lattices: Electronic and transport properties

Graphene bilayer systems are known to exhibit a band gap when the layer symmetry is broken, by applying a perpendicular electric field. The resulting band structure resembles that of a conventional semiconductor with a parabolic dispersion. Here, we introduce a novel bilayer graphene heterostructure, where single-layer graphene is placed on top of another layer of graphene with a regular lattice of antidots. We dub this class of graphene systems GOAL: graphene on graphene antidot lattice. By varying the structure geometry, band structure engineering can be performed to obtain linearly dispersing bands (with a high concomitant mobility), which nevertheless can be made gapped with the perpendicular field. We analyze the electronic structure and transport properties of various types of GOALs, and draw general conclusions about their properties to aid their design in experiments.Comment: 13 pages, 10 figures, submitte

Effect of IL-4 and IL-13 on IFN-γ-induced production of nitric oxide in mouse macrophages infected with herpes simplex virus type 2

AbstractInterleukin (IL)-4 and IL-13 share a wide range of activities. Prominent among these is the ability to antagonize many interferon (IFN)-γ-induced activities. Here we demonstrate that IL-4 and IL-13 totally abrogate IFN-γ-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA and protein synthesis in a murine macrophage cell line. IFN-γ-treated cells infected with herpes simplex virus type 2 (HSV-2) or costimulated with tumor necrosis factor (TNF)-α showed an enhanced reactivity, which was only partially reduced by IL-4/13. The results indicate that IL-4 and IL-13 function by intervening with a step prior to iNOS transcription by antagonizing IFN-γ-induced signal(s) without counteracting synergistic virus- or TNF-α-induced signals. The beneficial effect of a sustained NO production in foci of virus infection is suggested

Nonuniversal intensity correlations in 2D Anderson localizing random medium

Complex dielectric media often appear opaque because light traveling through them is scattered multiple times. Although the light scattering is a random process, different paths through the medium can be correlated encoding information about the medium. Here, we present spectroscopic measurements of nonuniversal intensity correlations that emerge when embedding quantum emitters inside a disordered photonic crystal that is found to Anderson-localize light. The emitters probe in-situ the microscopic details of the medium, and imprint such near-field properties onto the far-field correlations. Our findings provide new ways of enhancing light-matter interaction for quantum electrodynamics and energy harvesting, and may find applications in subwavelength diffuse-wave spectroscopy for biophotonics