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Mean free path

About: Mean free path is a research topic. Over the lifetime, 4412 publications have been published within this topic receiving 114418 citations.


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TL;DR: The excess current of a point contact on a Ag-Pb bilayer has been measured for several thicknesses of the Ag film and contains information about the position dependence of the superconducting order parameter near the interface.
Abstract: The excess current of a point contact on a Ag-Pb bilayer has been measured for several thicknesses of the Ag film. The excess current is due to Andreev reflection and contains information about the position dependence of the superconducting order parameter near the interface. If the Ag film is very thin, the excess current is that of a normal-metal--superconductor point contact, though slightly changed because of the depression of the order parameter at the surface of the bilayer. For larger thicknesses, the combination of the proximity effect and the limited mean free path of the electrons yields very different current-voltage characteristics.

73 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the electrical resistivity at 4.2°K and the mean free path at 2.5 µm in an ion-pumped ultrahigh-vacuum (UHV) system and in a conventional oil-pump UHV system on unheated glass substrates.
Abstract: Measurements of the electrical resistivity at 296° and 4.2°K in aluminum films, evaporated both in an ion‐pumped ultrahigh‐vacuum system and in conventional oil‐pumped systems onto unheated glass substrates, are presented and used to calculate the intrinsic mean free path and intrinsic electrical resistivity at 4.2°K. It is shown that the UHV films are characterized by a maximum mean free path of the order of 1 μ and by smaller residual resistances than other films. While the mean free path so obtained is still several orders of magnitude smaller than the published value for high‐purity foils of bulk aluminum, it is nevertheless not small enough to appreciably influence the resistivity at 296°K which is measured to be ≈60% higher than the bulk value. This discrepancy, which may be due to structural effects, emphasizes the view that the sample artifact of adding the bulk thermal resistivity to a residual resistivity can be misleading in the case of thin films, even when surface scattering is accounted for.

73 citations

Journal ArticleDOI
P Baille1, J S Chang1, A Claude1, R M Hobson1, G L Ogram1, Andrew W. Yau1 
TL;DR: In this article, the electron-neutral collision frequency in the noble gases has been calculated using recent numerical results for momentum transfer cross sections by assuming a Maxwellian distribution of electron velocities.
Abstract: The electron-neutral collision frequency in the noble gases has been calculated using recent numerical results for momentum transfer cross sections by assuming a Maxwellian distribution of electron velocities. In all these gases, except for argon, good agreement is obtained with most previously published experimental and theoretical data. Mean free path, mobilities and diffusion coefficients are also calculated from the resulting effective collision frequencies. The empirical formulae are presented for an electron temperature dependence of the electron-neutral collision frequency for all noble gases up to Te

73 citations

Journal ArticleDOI
TL;DR: In this article, the authors present measurements of S1 exciton transport in (6,5) carbon nanotubes at room temperature in a colloidal environment, and attribute the observed transport to disorder-limited diffusional transport associated with the dynamics of the colloidal interface.
Abstract: We present measurements of S1 exciton transport in (6,5) carbon nanotubes at room temperature in a colloidal environment. Exciton diffusion lengths associated with end quenching paired with photoluminescence lifetimes provide a direct basis for determining a median diffusion constant of approximately 7.5 cm2s–1. Our experimental results are compared to model diffusion constants calculated using a realistic exciton dispersion accounting for a logarithmic correction due to the exchange self-energy and a nonequilibrium distribution between bright and dark excitons. The intrinsic diffusion constant associated with acoustic phonon scattering is too large to explain the observed diffusion length, and as such, we attribute the observed transport to disorder-limited diffusional transport associated with the dynamics of the colloidal interface. In this model an effective surface potential limits the exciton mean free path to the same size as that of the exciton wave function, defined by the strength of the electro...

72 citations

Journal ArticleDOI
TL;DR: It is proved here that the recently observed universal conductance fluctuations in normal metals at very low temperatures are a rigorous consequence of that diffusion equation, in the regime in which L \ensuremath{\gg} (mean free path) and N\ensure Math{gg}1.
Abstract: Recently, a macroscopic theory of N-channel disordered condeuctors showed that the statistical distribution of the transfer matrix for a system of length L evolves with L according to a diffusion equation in N dimensions. It is proved here that the recently observed universal conductance fluctuations in normal metals at very low temperatures are a rigorous consequence of that diffusion equation, in the regime in which L\ensuremath{\gg} (mean free path) and N\ensuremath{\gg}1. The value found for the fluctuation coincides with the one obtained from elaborate microscopic calculations.

72 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202375
2022207
2021134
2020114
2019113
201887