Quantum impurity models play an important role as representations of molecular conductors and in the “dynamical mean field” method, currently one of the most promising tools for studying the physics of fermionic lattice models. Despite their zero-dimensional nature, the numerical simulation of impurity models remains a challenging task. Progress has been achieved with the recent development of ...

The basic motivation is to see what happens when we have a dopant/impurity in a metallic system where the Fermi level cuts through a band. Does the dopant in fact raise the Fermi level? By how much and in what circumstances? The question comes up when creating oxygen vacancies in a metallic oxide, for example an oxygen vacancy in LaNiO3. Clearly, there is a perturbation to the electronic struct...

Nanoelectronic device properties are usually influenced rather strongly by impurities and atomistic disorder. Examples are electron scattering by dopants in semiconductor nano-wires, spin scattering by disorder in magnetic tunnel junctions, and spin polarized current in dilute magnetic semiconductors. Theoretically, any calculated transport quantity must be averaged over the ensemble of possibl...

Alcator C-Mod is a high-field tokamak with which experiments were initiated in April 1993. The divertor and the first-wall have plasma-facing surfaces of molybdenum. The divertor has a configuration which is closed in comparison to other, currently operating tokamaks. The combination of divertor geometry and high field (density) make Alcator C-Mod an ideal experiment to investigate dissipative ...

Abstract. We investigate the influence of impurities and vacancies in the formation of magnetic moment in CaB6 using full potential ab initio band structure calculations. CaB6 is found to be a band insulator with a band gap of about 0.2 eV. The calculated results indicate that carbon and oxygen substitution in boron sublattice, usually expected as impurity in low purity borons, do not play sign...

The difference of temperatures between an impurity and the surrounding gas in an open vibrated granular system is studied. It is shown that, in spite of the high inhomogeneity of the state, the temperature ratio remains constant in the bulk of the system. The lack of energy equipartition is associated to the change of sign of the pressure diffusion coefficient for the impurity at certain values...

Grain-boundary grooving in an Al thin film was analyzed by molecular-dynamics simulation. The simulation result showed that the groove was formed by atom transport due to diffusion at the intersection of the grain-boundary and free surface. The effect of impurity on groove formation was analyzed in terms of atomic radius and bond energy. It was found that when the atomic radius of an impurity i...

The material-quality limiting factors of evaporated solid-phase crystallized (SPC) poly-Si thin films fabricated on planar glass for photovoltaic applications are investigated by a study combining scanning electron microscopy and transmission electron microscopy. The grains in the investigated thin films are found to be randomly oriented, with an average grain size of ~2.1 μm. In general, the g...

Ruthenium thin films are deposited by atomic layer deposition (ALD) from bis(N,N’-di-tert-butylacetamidinato)ruthenium(II) dicarbonyl and O2. Highly conductive, dense, and pure thin films can be deposited when oxygen exposure, EO, approaches a certain threshold (Emax). When EO>Emax the film peels off due to the recombinative desorption of O2 at the film/substrate interface. Analysis by atomic p...

We report on our latest results of K}Cs}Sb visible photocathodes, coated with thin CsI and CsBr protective "lms, for applications within gas avalanche photomultipliers. Data on the sensitivity to exposure to oxygen and moisture is presented, as well as on the stability under gas multiplication and aging under gas avalanche. There are good indications that the protected photocathodes can withsta...