Mesoscopic Transport in Tunable Andreev Interferometers

Vegvar, P. G. N. de; Fulton, T. A.; Mallison, W. H.; Miller, Ronald E.

doi:10.1103/physrevlett.73.1416

Cited by 94 publications

(75 citation statements)

References 15 publications

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“…The amplitude of modulation exceeds by several orders of magnitude the one observed in bigger structures at higher temperatures [6]. The authors doubt that their results can be explained by existing theories.…”

mentioning

confidence: 75%

“…There is an outburst of interest in this topic. Different types of Andreev interferometers have been proposed theoretically [2-4] and realized experimentally [5][6][7][8].Andreev scattering reveals a significant difference between diffusive conductors, from one side, and tunnel or quasiballistic junctions of the same resistance, from another side. Optimal interferometers are composed of tunnel junctions [4,5].…”

mentioning

confidence: 99%

“…There is an outburst of interest in this topic. Different types of Andreev interferometers have been proposed theoretically [2-4] and realized experimentally [5][6][7][8].…”

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confidence: 99%

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Diffusive Conductors as Andreev Interferometers

1996

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We theoretically study phase-dependent electrical transport in diffusive normal metal-superconductor structures, taking into account (a) the effect of electron-electron interaction in the normal metal and (b) the previously known "thermal" effect caused by the energy dependence of the diffusivity. Both effects cause changes in the resistance as a function of the phase between two superconductors, but effect (a) is already present at zero temperature, in contrast to effect (b). A detailed theoretical and numerical analysis demonstrates that the mechanism ( b) can fully explain recent experiments by Petrashov et al. [Phys. Rev. Lett. 74, 5268 (1995)]. PACS numbers: 74.50.+r, 74.80.Fp What is the resistance of a small normal structure adjacent to a superconductor? Superconductivity penetrates the structure provided it is short enough. A naive suggestion would be that the resistance vanishes. However, it is not so. The simplest way to see this is to relate the resistivity to the scattering in the structure [1]. Normal electrons traversing the structure should undergo scattering even if their wave functions are distorted by superconductivity.If the structure is connected to two superconducting terminals having different phases, the resistance of the structure will depend on the phase difference. This provides the physical background for what is called Andreev interferometry. There is an outburst of interest in this topic. Different types of Andreev interferometers have been proposed theoretically [2-4] and realized experimentally [5][6][7][8].Andreev scattering reveals a significant difference between diffusive conductors, from one side, and tunnel or quasiballistic junctions of the same resistance, from another side. Optimal interferometers are composed of tunnel junctions [4,5]. Ballistic and quasiballistic systems also show a big effect [2,7]. In contrast to this, the standard theory predicts that the zero-voltage, zerotemperature resistance of a diffusive conductor is not affected by penetrating superconductivity [9]. It is slightly modified at finite temperature, when the sample length becomes comparable to the superconducting correlation length in the normal metal, j p D͞pT, D being diffusivity. At higher temperatures, the resistance turns back to the same value. This is why the effect of Andreev scattering on the diffusive resistivity is eventually a thermal effect. Although this fact is well established and has been confirmed in the frameworks of several independent approaches, a simple physical explanation of the fact still is lacking. Apart from this thermal effect, a small modification may arise from the weak localization correction [10].However, the recent experiment [8] demonstrates a significant phase modulation of the resistivity in the small diffusive structures at very low temperatures. The amplitude of modulation exceeds by several orders of magnitude the one observed in bigger structures at higher temperatures [6]. The authors doubt that their results can be explained by existing theories.Below ...

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Diffusive Conductors as Andreev Interferometers

1996

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“…Furthermore, a number of quasiclassical predictions seem to be borne out well experimentally (see e.g. [34,[53][54][55][56][57]. In the field theoretic context introduced below, the Usadel equation and its boundary condition will reappear on the level of the mean field analysis in section VI.…”

Section: Solution Of the Usadel Equationmentioning

confidence: 95%

“…(52) and (53), this gives altogether four constraints and the nontrivial statement is that a set of generators W C obeying all of them actually exists. These are 11 Note that there is some freedom in parameterizing fluctuating field configurations.…”

Section: The C-modes: Non-perturbative Corrections To Quasiclassical mentioning

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Field theory of mesoscopic fluctuations in superconductor/normal-metal systems

1998

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Thermodynamic and transport properties of mesoscopic conductors are strongly influenced by the proximity of a superconductor: An interplay between the large scale quantum coherent wave functions in the normal mesoscopic and the superconducting region, respectively, leads to unusual mechanisms of quantum interference. These manifest themselves in both the mean and the mesoscopic fluctuation behaviour of superconductor/normal-metal (SN) hybrid systems being strikingly different from those of conventional mesoscopic systems. After reviewing some established theories of SN-quantum interference phenomena, we introduce a new approach to the analysis of SNmesoscopic physics. Essentially, our formalism represents a unification of the quasi-classical formalism for describing mean properties of SN-systems on the one hand, with more recent field theories of mesoscopic fluctuations on the other hand. Thus, by its very construction, the new approach is capable of exploring both averaged and fluctuation properties of SN-systems on the same microscopic footing. As an example, the method is applied to the study of various characteristics of the single particle spectrum of SNS-structures.

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