Nonequilibrium Josephson effect in short-arm diffusive SNS interferometers

Bezuglyĭ, E. V.; Shumeiko, Vitaly; Wendin, Göran

doi:10.1103/physrevb.68.134506

Cited by 19 publications

(16 citation statements)

References 43 publications

(54 reference statements)

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“…In the symmetric case G 2 = G 3 Eqs. (14)- (16) coincide with the corresponding expressions 17 . In order to interpret the result (16) in a general case G 2 = G 3 we recollect that the maximum transmission value T max for the system of two tunnel barriers with transmissions T 2 and T 3 (both much smaller than one) is defined by the well known formula…”

Section: Density Of States and Tunneling Currentmentioning

confidence: 90%

Andreev interferometer with three superconducting electrodes

2012

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We develop a quasiclassical theory of Andreev interferometers with three superconducting electrodes. Provided tunneling interface resistance between one superconducting electrode and the normal metal strongly exceeds two others, significant current sensitivity to the external magnetic flux is observed only at subgap voltages. If all barrier conductances are comparable, multiple Andreev reflection comes into play and substantial current modulation can be achieved in both subgap and overgap voltage regimes. Our analysis reveals a large variety of interesting features which can be used for performance optimization of Andreev interferometers.

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Section: Density Of States and Tunneling Currentmentioning

confidence: 90%

Andreev interferometer with three superconducting electrodes

2012

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“…Mesoscopic fluctuations of the DOS [23,24] are small provided G ≫ G Q . It looks like everything is understood, perhaps except a small dip or peak in the DOS just at the gap edge for the diffusive case, which has been seen in [3,5,[25][26][27][28], but never attracted proper attention.In this Letter, we demonstrate that the appearance of a secondary gap, in addition to the well-known gap ∼E Th in the DOS around the Fermi level, is a generic feature of S-N-S structure containing high-transmission S-N contacts. In the case of a chaotic cavity with two identical ballistic contacts, the secondary gap exists for any E Th > 0.68Δ and vanishes as Δ 3 =E…”

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confidence: 99%

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confidence: 99%

“Smile” Gap in the Density of States of a Cavity between Superconductors

et al. 2014

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The density of Andreev levels in a normal metal (N) in contact with two superconductors (S) is known to exhibit an induced minigap related to the inverse dwell time. We predict a small secondary gap just below the superconducting gap edge-a feature that has been overlooked so far in numerous microscopic studies of the density of states in S-N-S structures. In a generic structure with N being a chaotic cavity, the secondary gap is the widest at zero phase bias. It closes at some finite phase bias, forming the shape of a "smile". Asymmetric couplings give even richer gap structures near the phase difference π. All the features found should be amendable to experimental detection in high-resolution low-temperature tunneling spectroscopy. DOI: 10.1103/PhysRevLett.112.067001 PACS numbers: 74.45.+c, 74.78.Na The modification of the density of states (DOS) in a normal metal by a superconductor in its proximity was discovered almost 50 years ago [1]. Soon afterwards, it was predicted, theoretically, for diffusive structures that a socalled minigap of the order of the inverse dwell time in the normal metal (or the Thouless energy) appears in the spectrum [2]. The energy-dependent DOS reflects the energy scale of electron-hole decoherence, and is sensitive to the distance, the geometry, and the properties of the contact between the normal metal and the superconductor [3][4][5]. The details of the local density of states in proximity structures have been investigated experimentally many years later [6][7][8][9][10] and the theoretical predictions have been confirmed [11][12][13] Substantial interest has been paid to the density of states in a finite normal metal between two superconducting leads with different superconducting phases [14,15]. The difference between diffusive [5] and classical ballistic [16] dynamics has been investigated [17]. Many publications have addressed the dependence of the minigap on the competition between dwell and Ehrenfest time [18,19]. The most generic model in this context is that of a chaotic cavity, where a piece of normal metal is connected to the superconductors by means of ballistic point contacts that dominate the resistance of the structure in the normal state. The Thouless energy is given by E Th ¼ ðG Σ =G Q Þδ S , G Q ¼ e 2 =πℏ being the conductance quantum, G Σ ≫ G Q being the total conductance of the contacts, and δ S being the level spacing in the normal metal provided the contacts are closed. The DOS in chaotic cavities has been studied for years [19][20][21][22].The DOS depends on the ratio of E Th and the superconducting energy gap Δ, and on the superconducting phase difference. If the dwell time exceeds the Ehrenfest time, qualitative features of the DOS do not seem to depend much on the contact nature and are the same for ballistic, diffusive, and tunnel contacts. Mesoscopic fluctuations of the DOS [23,24] are small provided G ≫ G Q . It looks like everything is understood, perhaps except a small dip or peak in the DOS just at the gap edge for the diffusive case, which has ...

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“…where K is the elliptic integral. These results have also been derived by another methods for the chaotic quantum dot in ergodic regime 34 and for a diffusive junctions with equal 25,27 and asymmetric 23 barriers.…”

Section: Equilibrium Josephson Current and The Minigap Functionmentioning

confidence: 63%

Current–voltage characteristics of asymmetric double-barrier Josephson junctions

Bezuglyĭ

Bratus

Shumeiko

2014

Physica C: Superconductivity

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We develop a theory for the current-voltage characteristics of diffusive superconductor-normal metal-superconductor Josephson junctions with resistive interfaces and the distance between the electrodes smaller than the superconducting coherence length. The theory allows for a quantitative analytical and numerical analysis in the whole range of the interface transparencies and asymmetry. We focus on the regime of large interface resistance compared to the resistance of the normal region, when the electron-hole dephasing in the normal region is significant and the finite length of the junction plays a role. In the limit of strong asymmetry we find pronounced current structures at the combination subharmonics of ∆ + ∆ g , where ∆ g is the proximity minigap in the normal region, in addition to the subharmonics of the energy gap 2∆ in the electrodes. In the limit of rather transparent interfaces, our theory recovers a known formula for the current in a short mesoscopic connector -a convolution of the current through a single-channel point contact with the transparency distribution for an asymmetric double-barrier potential.

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Nonequilibrium Josephson effect in short-arm diffusive SNS interferometers

Cited by 19 publications

References 43 publications

Andreev interferometer with three superconducting electrodes

Andreev interferometer with three superconducting electrodes

“Smile” Gap in the Density of States of a Cavity between Superconductors

Current–voltage characteristics of asymmetric double-barrier Josephson junctions

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