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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 construction of a mechanically controlled break-junction setup (MCBJ) equipped with a highly sensitive log I–V converter in order to measure ultralow conductances of molecular rods trapped between two gold leads is described.
Abstract: π-Conjugation plays an important role in charge transport through single molecular junctions We describe in this paper the construction of a mechanically controlled break-junction setup (MCBJ) equipped with a highly sensitive log I–V converter in order to measure ultralow conductances of molecular rods trapped between two gold leads The current resolution of the setup reaches down to 10 fA We report single-molecule conductance measurements of an anthracene-based linearly conjugated molecule (AC), of an anthraquinone-based cross-conjugated molecule (AQ), and of a dihydroanthracene-based molecule (AH) with a broken conjugation The quantitative analysis of complementary current–distance and current–voltage measurements revealed details of the influence of π-conjugation on the single-molecule conductance
165 citations
TL;DR: In this article, the electronic conductance of metal nanocontacts is analyzed in terms of eigenchannels for the transmission, and the transmission through individual eigen channels is calculated numerically for realistic models of gold point contacts based on molecular-dynamics simulation of the elongation of a contact.
Abstract: The electronic conductance of metal nanocontacts is analyzed in terms of eigenchannels for the transmission. The transmission through individual eigenchannels is calculated numerically for realistic models of gold point contacts based on molecular-dynamics simulation of the elongation of a contact. The conductance as a function of contact elongation exhibits a step structure. For the smallest contact areas of one or a few atom diameters, the conductance is typically quantized, and a specific number of almost open eigenchannels can be ascribed. For larger contact areas the scattering leads to partly open channels, but plateaus in the conductance can still be present. We also show that the finite stiffness of the experimental setup can significantly affect the step structure of the conductance curves. @S0163-1829~97!05047-9# Electrical transport in structures with a size on the order of the Fermi wavelength (l F) has been studied intensely in the last decade. For these systems, the conductance is determined by the quantum-mechanical transmission. This was demonstrated clearly by the conductance quantization ~CQ!, which was first observed in fabricated semiconductor structures. 1 More recently the tendency for CQ in nanocontacts of certain metals, especially the single s-valence metals Au, 2,3 Na, 4 Cu, and Ag, 5 was established. In contrast to the former case, the atomic discreteness of the latter systems is of importance in two respects: ~i! The contact narrows in ‘‘jumps’’ upon elongation due to atomic rearrangements. 6 This gives rise to jumps in the conductance and tensile force. 7,3,8‐11 ~ii! The potential confining the electrons inside the contact is corrugated on an atomic length scale which is close to l F . Thus the relevance of the adiabatic picture, 12 with well-defined quantized transmission channels, is far from obvious. We introduce and calculate numerically the general eigenchannel transmissions of realistic models of gold metal nanocontacts. The eigenchannels are defined such that an unambiguous transmission can be assigned to each individual eigenchannel. Thus the conductance is uniquely split into eigenchannel contributions. As an input into the calculations we use molecular-dynamics ~MD! simulations of the elongation of nanocontacts. Our results explicitly show a change in character of the steps in the conductance curves. For very small contact areas, plateaus in the conductance are essentially due to a certain number of open eigenchannels. For a single atom contact, for example, a single eigenchannel is seen to carry almost all the transport. For larger contact areas the picture changes: Due to scattering, partly open channels contribute to the conductance, and the plateaus must be associated with mechanical properties of the contact. The scattering is almost entirely determined by the one-electron potential at the narrowest point. Finally, we show that the observation of plateaus in the conductance curve for the larger contacts will depend significantly on the stiffness of the experimental setup. The conductance can be calculated from the multichannel
165 citations
TL;DR: In this paper, the authors analyzed the thermal and electrical properties of perfect GNRs as a function of their width and their edge orientation to identify a strategy likely to degrade the thermal conductance while retaining high electronic conductance and thermopower.
Abstract: Strongly enhanced thermoelectric properties are predicted for graphene nanoribbons (GNRs) with optimized pattern By means of nonequilibrium Green's function atomistic simulation of electron and phonon transport, we analyze the thermal and electrical properties of perfect GNRs as a function of their width and their edge orientation to identify a strategy likely to degrade the thermal conductance while retaining high electronic conductance and thermopower An effect of resonant tunneling of electrons is detected in mixed GNRs consisting of alternate zigzag and armchair sections To fully benefit from this effect and from strongly reduced phonon thermal conductance, a structure with armchair and zigzag sections of different widths is proposed It is shown to provide a high thermoelectric factor of merit $\mathit{ZT}$ exceeding unity at room temperature
164 citations
TL;DR: The single channel conductance displays an anomalous molefraction effect in symmetric mixtures of K+ and NH+4, suggesting that the conducting pore is occupied by multiple ions simultaneously.
164 citations
TL;DR: In this article, the authors observed that the initial reaction of EIM with the lipid membranes are remarkably uniform, even in membranes of widely varying lipid composition, and that the transition between high conductance and low conductance states may involve steps as small as 0.5 x 10-10 ohm-1.
Abstract: Discrete fluctuations in conductance of lipid bilayer membranes may be observed during the initial stages of membrane interaction with EIM ("excitability inducing material"), during destruction of the EIM conductance by proteolysis, and during the potential-dependent transitions between low and high conductance states in the "excitable" membranes. The discrete conductance steps observed during the initial reaction of EIM with the lipid membranes are remarkably uniform, even in membranes of widely varying lipid composition. They range only from 2 to 6 x 10-10 ohm-1 and average 4 x 10-10 ohm-1. Steps found during destruction of the EIM conductance by proteolysis are somewhat smaller. The transition between high conductance and low conductance states may involve steps as small as 0.5 x 10-10 ohm-1. These phenomena are consistent with the formation of a stable protein bridge across the lipid membrane to provide a polar channel for the transport of cations. T6he uniform conductance fluctuations observed during the formation of these macromolecular channels may indicate that the ions in a conductive channel, in its open state, are largely protected from the influence of the polar groups of the membrane lipids. Potential-dependent changes in conductance may be due to configurational or positional changes in the protein channel. Differences in lipid-lipid and lipid-macromolecule interactions may account for the variations in switching kinetics in various membrane systems.
164 citations