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Conductance
About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.
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TL;DR: The effects of impurities and local structural defects on the conductance of metallic carbon nanotubes are calculated using an ab initio pseudopotential method within the Landauer formalism and shows a much more complex behavior than the prediction from the widely used pi-electron tight-binding model.
Abstract: The effects of impurities and local structural defects on the conductance of metallic carbon nanotubes are calculated using an ab initio pseudopotential method within the Landauer formalism. Substitutionally doped boron or nitrogen produces quasibound impurity states of a definite parity and reduces the conductance by a quantum unit $({2e}^{2}/h)$ via resonant backscattering. These resonant states show strong similarity to acceptor or donor states in semiconductors. The Stone-Wales defect also produces quasibound states and exhibits quantized conductance reduction. In the case of a vacancy, the conductance shows a much more complex behavior than the prediction from the widely used $\ensuremath{\pi}$-electron tight-binding model.
455 citations
TL;DR: The observation of a light-induced anomalous Hall effect in monolayer graphene driven by a femtosecond pulse of circularly polarized light reveals multiple features that reflect a Floquet-engineered topological band structure similar to the band structure originally proposed by Haldane 10 .
Abstract: Many non-equilibrium phenomena have been discovered or predicted in optically driven quantum solids1. Examples include light-induced superconductivity2,3 and Floquet-engineered topological phases4–8. These are short-lived effects that should lead to measurable changes in electrical transport, which can be characterized using an ultrafast device architecture based on photoconductive switches9. Here, we report the observation of a light-induced anomalous Hall effect in monolayer graphene driven by a femtosecond pulse of circularly polarized light. The dependence of the effect on a gate potential used to tune the Fermi level reveals multiple features that reflect a Floquet-engineered topological band structure4,5, similar to the band structure originally proposed by Haldane10. This includes an approximately 60 meV wide conductance plateau centred at the Dirac point, where a gap of equal magnitude is predicted to open. We find that when the Fermi level lies within this plateau the estimated anomalous Hall conductance saturates around 1.8 ± 0.4 e2/h. A transient topological response in graphene is driven by a short pulse of light. When the Fermi energy is in the predicted band gap the Hall conductance is around two conductance quanta. An ultrafast detection technique enables the measurement.
454 citations
TL;DR: An increase in the number of functional conductance channels by adrenaline is discussed as a possible mechanism for the increase in Gs, which was greatly increased by the voltage‐clamp method.
Abstract: 1. The effect of adrenaline on the Ca-dependent slow inward current, Is, of mammalian cardiac muscle has been investigated by the voltage-clamp method. The mechanism of the increase in the conductance, gs, was analysed on the basis of a kinetic scheme (Hodgkin & Huxley, 1952) applicable to this system. 2. The rate constants alphad and betad, of activation of gs were not influenced by adrenaline, although the limiting conductance, gs, was greatly increased. 3. Reduction of [Ca]o from 1-8 to 0-2 mM decreased the amplitude of inward tail currents when gs was fully activated; however, the relative decrease of the current amplitude was the same with and without adrenaline. The reversal potential, ER, of Is was not changed by the drug. This indicates that the catecholamine has no influence on the selectivity of these conductance channels. 4. An increase in the number of functional conductance channels by adrenaline is discussed as a possible mechanism for the increase in Gs.
454 citations
TL;DR: It is observed that deformation occurs as a sequence of structural transformations involving elastic and yielding stages and that force and conductance before rupture have definite values which are likely to correspond to a single atom contact.
Abstract: Measuring simultaneously the force and the conductance during the formation and rupture of an atomic-sized gold contact at room temperature, we observe that deformation occurs as a sequence of structural transformations involving elastic and yielding stages and that force and conductance before rupture have definite values which are likely to correspond to a single atom contact. We measure the mechanical properties of contacts consisting of only a few atoms and show that the stepwise variation of the conductance is always due to the atomic rearrangements in the contact.
451 citations
TL;DR: This work measures the conductance and mechanical characteristics of a single polyfluorene wire by pulling it up from a Au(111) surface with the tip of a scanning tunneling microscope, thus continuously changing its length up to more than 20 nanometers.
Abstract: The development of electronic devices at the single-molecule scale requires detailed understanding of charge transport through individual molecular wires. To characterize the electrical conductance, it is necessary to vary the length of a single molecular wire, contacted to two electrodes, in a controlled way. Such studies usually determine the conductance of a certain molecular species with one specific length. We measure the conductance and mechanical characteristics of a single polyfluorene wire by pulling it up from a Au(111) surface with the tip of a scanning tunneling microscope, thus continuously changing its length up to more than 20 nanometers. The conductance curves show not only an exponential decay but also characteristic oscillations as one molecular unit after another is detached from the surface during stretching.
445 citations