9 research outputs found
Resummation scheme for 3d Yang-Mills and the two-loop magnetic mass for hot gauge theories
Perturbation theory for non-Abelian gauge theories at finite temperature is
plagued by infrared divergences caused by magnetic soft modes ,
which correspond to the fields of a 3d Yang-Mills theory. We revisit a gauge
invariant resummation scheme to solve this problem by self-consistent mass
generation using an auxiliary scalar field, improving over previous attempts in
two respects. First, we generalise earlier SU(2) treatments to SU(N). Second,
we obtain a gauge independent two-loop gap equation, correcting an error in the
literature. The resulting two-loop approximation to the magnetic mass
represents a correction to the leading one-loop value, indicating a
reasonable convergence of the resummation.Comment: 16 pages, 3 figure
Space Charge at Nanoscale: Probing Injection and Dynamic Phenomena Under Dark/Light Configurations by Using KPFM and C-AFM
International audienc
Using metallic noncontact atomic force microscope tips for imaging insulators and polar molecules: tip characterization and imaging mechanisms
We demonstrate that using metallic tips for noncontact atomic force microscopy (NC-AFM) imaging at relatively large (>0.5 nm) tip-surface separations provides a reliable method for studying molecules on insulating surfaces with chemical resolution and greatly reduces the complexity of interpreting experimental data. The experimental NC-AFM imaging and theoretical simulations were carried out for the NiO(001) surface as well as adsorbed CO and Co-Salen molecules using Cr-coated Si tips. The experimental results and density functional theory calculations confirm that metallic tips possess a permanent electric dipole moment with its positive end oriented toward the sample. By analyzing the experimental data, we could directly determine the dipole moment of the Cr-coated tip. A model representing the metallic tip as a point dipole is described and shown to produce NC-AFM images of individual CO molecules adsorbed onto NiO(001) in good quantitative agreement with experimental results. Finally, we discuss methods for characterizing the structure of metal-coated tips and the application of these tips to imaging dipoles of large adsorbed molecules. © 2014 American Chemical Society
Activation of Ultrathin Oxide Films for Chemical Reaction by Interface Defects
Periodic density functional theory calculations revealed strong enhancement of chemical reactivity by defects located at the oxide-metal interface for water dissociation on ultrathin MgO films deposited on Ag(100) substrate. Accumulation of charge density at the oxide-metal interface due to irregular interface defects influences the chemical reactivity of MgO films by changing the charge distribution at the oxide surface. Our results reveal the importance of buried interface defects in controlling chemical reactions on an ultrathin oxide film supported by a metal substrate.close1