Showing papers by "Yoseph Imry published in 1985"
TL;DR: The dependence on channel number N of the contributions to the conductance of a small ring, periodic in the Aharonov-Bohm flux through it is obtained, and terms whose period is h/e as well as those with period h/2e vary with N as 1/N.
Abstract: The conductance of a sample scattering elastically and coupled to leads with many channels is derived. We assume that all the incident channels on one side of the sample are fed from the same chemical potential. The transmitted and reflected streams are determined by the incident streams through the multichannel scattering properties of the sample. We do not assume that the channels equilibrate with each other. Our result differs from those given earlier by other authors, except for that of Azbel [J. Phys. C 14, L225 (1981)], which is confirmed. We point out that a similar result is obtained for the conductance in a single channel at a temperature above zero. As an application, we obtain the dependence on channel number N of the contributions to the conductance of a small ring, periodic in the Aharonov-Bohm flux through it. Terms whose period is h/e as well as those with period h/2e vary with N as 1/N.
2,513 citations
TL;DR: In this article, the conductance of a loop shorter than the inelastic diffusion length, connected to leads with many quantum channels, can be asymmetric under magnetic field reversal.
Abstract: The conductance of a loop shorter than the inelastic diffusion length, connected to leads with many quantum channels, can be asymmetric under magnetic field reversal.
22 citations
TL;DR: In this article, the field dependence of the magnetoconductance in finite-geometry samples is analyzed within the framework of the localization theory, and the crossover point is obtained once the radius of the Landau level becomes smaller than the sample thickness for both the parallel and the perpendicular field orientations.
Abstract: The field dependence of the magnetoconductance in finite-geometry samples is analyzed within the framework of the localization theory. It is found that for high magnetic fields the magnetoconductance acquires the functional field dependence characteristic of a three-dimensional system. This is so even when the inelastic mean free path is much larger than the sample thickness and when the zero-field transport properties of the system are two dimensional in character. The crossover point is obtained once the radius of the Landau level becomes smaller than the sample thickness for both the parallel and the perpendicular field orientations. These theoretical considerations are borne out by experiments on indium oxide films.
17 citations
TL;DR: In this paper, the conductivity of approximately 50 AA thin indium oxide films was studied as a function of temperature around and below the cross-over to strong localisation, with a fine tuning of the room-temperature sheet resistance.
Abstract: The conductivity of approximately 50 AA thin effectively two-dimensional indium oxide films was studied as a function of temperature around and below the cross-over to strong localisation, with a fine tuning of the room-temperature sheet resistance. When the latter is in an extremely narrow range around 50 k Omega / Square Operator , a conductivity proportional to T over a broad range was obtained. The results were interpreted using a hopping mechanism, suggested by Gogolin, Mel'nikov and Rashba, (1975) and by Thouless (1977). General conditions to obtain this power-law behaviour in any dimension were formulated.
11 citations
TL;DR: In this article, it was shown that in a realistic small enough loop-type normal conducting structure at low temperatures, interesting oscillations may be observed with an applied magnetic field through the hole of the loop.
Abstract: I n this paper it is shown that in a realistic small enough loop-type normal conducting structure at low temperatures, interesting oscillations may be observed with an applied magnetic field through the hole of the loop. This touches upon several fundamental questions and may, in principle, be applied to a variety of supersmall extra-sensitive devices that up to now have been considered only employing superconducting metals. That electrons may also exhibit wavelike phenomena is now a well-known and an experimentally well-documented observation. Electron waves exhibit interference phenomena which, in fact, offer one of the powerful methods for analyzing the structure of matter. The duality between particles and waves is one of the fundamental concepts of quantum mechanics and one that has caused profound changes in our understanding of the physical world. A further curious prediction of quantum mechanics, which was advanced in 1959 by Yakir Aharonov and David Bohm, is that the above-mentioned interference effects may be sensitive to magnetic fields that act in regions of space totally removed from where the electrons can be found.’ Thus, if an election beam is split and then combined to interfere a t a further point in space, the obtained interference pattern is sensitive to magnetic fields in the hollow between the two branches. It will move with the above magnetic flux and the results are periodic in a “flux quantum” 4,, Z= 4 x (in MKS units). What is important is only the amount of flux beyond an integer multiple of I$,,. The aforementioned electron beams have to mave in vacuum so as not to be affected by air molecules, dust particles, etc. A lot of such scattering will scramble the delicate phase relationships enough to wash out these interference patterns. One would thus be inclined to expect that as far as the motion of electrons in ordinary conductors in which enough scattering practically always exists is concerned, this sort of interference should not exist. An important exception to this is the special case of superconductors-a state of metals where bound electron pairs can carry currents without experiencing ordinary electrical resistance and scattering. Here, interference phenomena do exist and yield important new effects, such as the quantization of magnetic flux2 and the Josephson effects’ involving, among other things, a relationship between the ordinary voltage and the frequency of spontaneously generated alternating (AC) current between two appropriately coupled superconductors. These effects already have many applications ranging from frequency standards to extremely sensitive measurement and other electronic devices. In an extremely interesting paper Felix Bloch showed some time ago that these effects are indeed related to general quantum mechanical principle^,^ associated in fact with the Aharonov-Bohm picture.* The generality of these considerations has led several people to speculate about