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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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Journal ArticleDOI
TL;DR: Findings demonstrate that charge transport through single organic molecules at ambient temperatures is a subtle and highly dynamic process that cannot be described by analysing only one molecular conformation corresponding to the lowest energy geometry of the molecule.
Abstract: The temperature dependence of the single molecule conductance (SMC) of α,ω-alkanedithiols has been investigated using a scanning tunnelling microscopy (STM) method. This is based on trapping molecules between a gold STM tip and a gold substrate and measuring directly the current across the molecule under different applied potentials. A pronounced temperature dependence of the conductance, which scales logarithmically with T−1, is observed in the temperature range between 293 and 353 K. It is proposed that the origin of this dependence is the change in distribution between molecular conformers rather than changes in either the conduction mechanism or the electronic structure of the molecule. For alkanedithiols the time averaged conformer distribution shifts to less elongated conformers at higher temperatures thus giving rise to higher conductance across the molecular bridges. This is analysed by first calculating energy differences between different conformers and then calculating their partition distribution. A simple tunnelling model is then used to calculate the temperature dependent conductance based on the conformer distribution. These findings demonstrate that charge transport through single organic molecules at ambient temperatures is a subtle and highly dynamic process that cannot be described by analysing only one molecular conformation corresponding to the lowest energy geometry of the molecule.

112 citations

Journal ArticleDOI
TL;DR: In this article, an experimental protocol which allows to perform conductance spectroscopy on organic molecules at low temperatures (T≈30 K) has been developed, which extends the method of mechanically controlled break junctions which has recently demonstrated to be suitable to contact single molecules at room temperature.
Abstract: An experimental protocol which allows to perform conductance spectroscopy on organic molecules at low temperatures (T≈30 K) has been developed. This extends the method of mechanically controlled break junctions which has recently demonstrated to be suitable to contact single molecules at room temperature. The conductance data obtained at low T with a conjugated sample molecule show a highly improved data quality with a higher stability, narrower linewidth, and substantially reduced noise. Thus, the comparability of experimental data with other measurements as well as with theoretical simulations is considerably improved.

112 citations

Journal ArticleDOI
TL;DR: In the case of isotropic Kondo exchange it is found that the correction to the electrical conductance caused by such an impurity vanishes in the dc limit, while the thermal conductance does acquire a finite correction due to the spin-flip backscattering.
Abstract: Transport in an ideal two-dimensional quantum spin Hall device is dominated by the counterpropagating edge states of electrons with opposite spins, giving the universal value of the conductance, $2{e}^{2}/h$. We study the effect on the conductance of a magnetic impurity, which can backscatter an electron from one edge state to the other. In the case of isotropic Kondo exchange we find that the correction to the electrical conductance caused by such an impurity vanishes in the dc limit, while the thermal conductance does acquire a finite correction due to the spin-flip backscattering.

112 citations

Journal ArticleDOI
TL;DR: Numerical results show that the lowest plateau can survive for a very broad range of disorder strength, but the existence of high plateaus depends on system parameters and sometimes cannot be formed at all.
Abstract: We investigate the electron transport through a graphene p-n junction under a perpendicular magnetic field. By using the Landauer-Buttiker formalism combined with the nonequilibrium Green function method, the conductance is studied for clean and disordered samples. For the clean p-n junction, the conductance is quite small. In the presence of disorders, it is strongly enhanced and exhibits a plateau structure at a suitable range of disorders. Our numerical results show that the lowest plateau can survive for a very broad range of disorder strength, but the existence of high plateaus depends on system parameters and sometimes cannot be formed at all. When the disorder is slightly outside of this disorder range, some conductance plateaus can still emerge with its value lower than the ideal value. These results are in excellent agreement with a recent experiment.

112 citations

Journal ArticleDOI
TL;DR: In this paper, the dynamical conductance of electrically contacted single-walled carbon nanotubes is measured from dc to 10 GHz as a function of source-drain voltage in both the low field and high field limits.
Abstract: The dynamical conductance of electrically contacted single-walled carbon nanotubes is measured from dc to 10 GHz as a function of source-drain voltage in both the low-field and high-field limits. The ac conductance of the nanotube itself is found to be equal to the dc conductance over the frequency range studied for tubes in both the ballistic and diffusive limit. This clearly demonstrates that nanotubes can carry high-frequency currents at least as well as dc currents over a wide range of operating conditions. Although a detailed theoretical explanation is still lacking, we present a phenomenological model of the ac impedance of a carbon nanotube in the presence of scattering that is consistent with these results.

112 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023457
2022828
2021154
2020158
2019172
2018168