Effect of line defects on the electrical transport properties of monolayer MoS2_{2} sheet

We present a computational study on the impact of line defects on the electronic properties of monolayer MoS2. Four different kinds of line defects with Mo and S as the bridging atoms, consistent with recent theoretical and experimental observations are considered herein. We employ the density functional tight-binding (DFTB) method with a Slater-Koster type DFTB-CP2K basis set for evaluating the material properties of perfect and the various defective MoS2 sheets. The transmission spectra is computed with a DFTB-Non-Equilibrium Greens Function (NEGF) formalism. We also perform a detailed analysis of the carrier transmission pathways under a small bias and investigate the phase shifts in the transmission eigenstates of the defective MoS2 sheets. Our simulations show a 2-4 folds decrease in carrier conductance of MoS2 sheets in the presence of line defects as compared to that for the perfect sheet

Spontaneous breaking of time reversal symmetry in strongly interacting two dimensional electron layers in silicon and germanium

We report experimental evidence of a remarkable spontaneous time reversal symmetry breaking in two dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P $\delta-$layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two dimensional electrons are confined to narrow half-filled impurity bands

Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots

We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis either rotates in the opposite direction to that of the magnetic field or remains fixed to a given crystalline direction. A theoretical analysis based on the exciton pseudospin Hamiltonian unambiguously demonstrates that these effects are induced by isotropic and anisotropic contributions to the heavy-hole Zeeman term, respectively. The latter is shown to be compensated by a built-in uniaxial anisotropy in a magnetic field B_c = 0.4 T, resulting in an optical response typical for symmetric quantum dots.Comment: 5 pages, 3 figure

A tachyonic extension of the stringy no-go theorem

We investigate the tachyon-dilaton-metric system to study the "graceful exit" problem in string theoretic inflation, where tachyon plays the role of the scalar field. From the phase space analysis, we find that the inflationary phase does not smoothly connect to a Friedmann-Robertson-Walker (FRW) expanding universe, thereby providing a simple tachyonic extension of the recently proved stringy no-go theorem.Comment: TeX file (PHYZZX), 10 pages, change in the title, many changes in the text (the version to appear in Phys. Rev. D

Socio-Economic Analysis of Effectiveness of Implementation of an Employment Guarantee Scheme at Local Level: A Study of a Village in India

The main purpose of the study is to develop theoretical and practical principles for analyzing the economic efficiency of the program to guarantee employment in rural areas in India. This program of support and active promotion of employment of the rural population is the result of the adoption of the Law on Guarantees of Employment in Rural Areas. The relevance of the choice of this scientific problem is that most scientific papers focus on assessing the effectiveness of the implementation of this legal act at the macro level, while the article analyzes this issue at the level of a particular locality

Blood-based bioenergetic profiling is related to differences in brain morphology in African Americans with Type 2 diabetes.

Blood-based bioenergetic profiling has promising applications as a minimally invasive biomarker of systemic bioenergetic capacity. In the present study, we examined peripheral blood mononuclear cell (PBMC) mitochondrial function and brain morphology in a cohort of African Americans with long-standing Type 2 diabetes. Key parameters of PBMC respiration were correlated with white matter, gray matter, and total intracranial volumes. Our analyses indicate that these relationships are primarily driven by the relationship of systemic bioenergetic capacity with total intracranial volume, suggesting that systemic differences in mitochondrial function may play a role in overall brain morphology

Optimization of Gate Leakage and NBTI for Plasma-Nitrided Gate Oxides by Numerical and Analytical Models

Reduction in static-power dissipation (gate leakage) by using nitrided oxides comes at the expense of enhanced negative-bias temperature instability (NBTI). Therefore, determining the nitrogen content in gate oxides that can simultaneously optimize gate-leakage and NBTI degradation is a problem of significant technological relevance. In this paper, we experimentally and theoretically analyze wide range of gate-leakage and NBTI stress data from a variety of plasma-oxynitride gate dielectric devices to establish an optimization scheme for gate-leakage and NBTI degradation. Calculating electric fields and leakage current both numerically and using simple analytical expressions, we demonstrate a design diagram for arbitrary nitrogen concentration and effective oxide thickness that may be used for process and IC design

Alumina silicon oxycarbide hybrids

Alumina-silicon oxycarbide (from polyphenylmethlsilsesquioxane which is fired in absence of air)batch is synthesized using propanol solution and magnetic stirring. Three batches of different composition are made, ,polyphenylmethylsilsesquoxane being the major constituent (i.e-70:30;80:20;90:10). The polymer will form a coating on the alumina surface. To ensure coating of the alumina surface, polyphenylmethylsilsesquioxane is added first and it is then allowed to dissolve completely by stirring for 15-20 minutes. Then the required amount of alumina is added gradually to the polyphenylmethylsilsesquioxane solution and stirred vigorously for next 20-25 minutes and ensure its complete solution. The powder is pyrolysed at 400¢ªC, 500¢ªC,600¢ªC,800¢ªC and 900¢ªC. After the pyrolysis, the overall volume of the composite decreases and the composite becomes more dense.Then characterization of the pyrolysed powder is done by XRD, BET and UV-VIS Spectroscopy.BET was done to study the pore size/volume and surface area of these hybrid. UV-VIS spectroscopy was performed to study the preliminary adsorption properties of these hybrids for toxic ion removal