Browsing by Subject "Ballistics"

Now showing 1 - 4 of 4

Open Access
Disorder-free localization around the conduction band edge of crossing and kinked silicon nanowires
(A I P Publishing LLC, 2015) Keleş, Ü.; Çakan, A.; Bulutay, C.
We explore ballistic regime quantum transport characteristics of oxide-embedded crossing and kinked silicon nanowires (NWs) within a large-scale empirical pseudopotential electronic structure framework, coupled to the Kubo-Greenwood transport analysis. A real-space wave function study is undertaken and the outcomes are interpreted together with the findings of ballistic transport calculations. This reveals that ballistic transport edge lies tens to hundreds of millielectron volts above the lowest unoccupied molecular orbital, with a substantial number of localized states appearing in between, as well as above the former. We show that these localized states are not due to the oxide interface, but rather core silicon-derived. They manifest the wave nature of electrons brought to foreground by the reflections originating from NW junctions and bends. Hence, we show that the crossings and kinks of even ultraclean Si NWs possess a conduction band tail without a recourse to atomistic disorder.
Open Access
Finite size effects in cooperative molecular motors
(Elsevier B.V., 2003) Taneri, S.; Yalabik, M. C.
We have studied the ballistic and damped dynamics of finite size cooperative molecular motors. We study the effect of finite size on average quantities such as sliding velocity, as well as the statistics of fluctuations in these quantities. We observed stalling for the over damped case.
Open Access
High-conducting magnetic nanowires obtained from uniform titanium-covered carbon nanotubes
(American Physical Society, 2004) Daǧ, Sefa; Durgun, Engin; Çıracı, Salim
We have shown that a semiconducting single-wall carbon nanotube (SWNT) can be covered uniformly by titanium atoms and form a complex but regular atomic structure. The circular cross section changes to a squarelike form, and the system becomes metallic with high state density at the Fermi level and with high quantum ballistic conductance. Metallicity is induced not only by the metal-metal coupling, but also by the band-gap closing of SWNT's at the corners of the square. Even more interesting is that uniform titanium-covered tubes have magnetic ground state with significant net magnetic moment. Our results have been obtained by the first-principles pseudopotential plane-wave calculations within the density-functional theory.
Open Access
Point normal metal-superconductor (NS) contact in nonballistic regime
(World Scientific Publishing, 2003) Askerzade, İ. N.; Kulik, Igor Orestovich
We analyze the point NS contact conductivity taking into account the depression of superconductivity at high-injection current density and Andreev reflection at the adaptive NS boundary. The dependence of the excess current on the voltage, as well as conductivity of contact at arbitrary voltage is obtained.