Proximity dc squids in the long-junction limit

Angers, L.; Chiodi, F.; Montambaux, Gilles; Ferrier, M.; Guéron, S.; Bouchiat, H.; Cuevas, Juan Carlos

doi:10.1103/physrevb.77.165408

Cited by 103 publications

(152 citation statements)

References 49 publications

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“…We emphasize also that in LTS S-N-S junctions the appearance of hysteresis has been explained, within the RCSJ model, through an effective capacitance proportional to a diffusion time, which in turn is inversely proportional to the Thouless energy. 19,20 This has remarkable similarities with the conclusions of one our previous works. 21 …”

Section: -2supporting

confidence: 79%

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Stornaiuolo

Rotoli

Cedergren

et al. 2010

Journal of Applied Physics

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We report a systematic study of the transport properties of high critical temperature superconductor ͑HTS͒ biepitaxial Josephson junctions in the submicron range. Junction performances point to more uniform and reproducible devices and to better control of d-wave intrinsic properties. Outcomes promote novel insights into the transport mechanisms across grain boundaries and encourage further developments in the control of dissipation in HTS devices. The application of nanotechnology to HTS could be an additional tool to properly engineer the junction properties to match specific circuit design also in view of the integration into hybrid quantum circuits.

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Section: -2supporting

confidence: 79%

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Stornaiuolo

Rotoli

Cedergren

et al. 2010

Journal of Applied Physics

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“…In contrast to wide S/semiconductor/S Josephson junctions, 27 no Fraunhofer-type interference pattern of I c (B) is observed. The absence of a magnetic interference pattern in SNS structures was first observed by Anger et al 28 and theoretically explained by Hammer et al 16 and Cuevas and Bergeret. 17 The reason for the monotonous decay of I c is that for junctions with a width smaller than the magnetic length ξ B the magnetic field acts as a pairbreaking factor.…”

mentioning

confidence: 91%

Josephson supercurrent in Nb/InN-nanowire/Nb junctions

Frielinghaus

Batov

Weides

et al. 2010

Applied Physics Letters

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We experimentally studied the Josephson supercurrent in Nb/InN-nanowire/Nb junctions. Large critical currents up to 5.7 µA have been achieved, which proves the good coupling of the nanowire to the superconductor. The effect of a magnetic field perpendicular to the plane of the Josephson junction on the critical current has been studied. The observed monotonous decrease of the critical current with magnetic field is explained by the magnetic pair-breaking effect in planar Josephson junctions of ultra-narrow width [J. C. Cuevas and F. S. Bergeret, Phys. Rev. Lett. 99, 217002 (2007)] Superconductor/normal-conductor/superconductor (SNS) junctions with a semiconductor employed as the N-weak link material offer the great advantage that here the Josephson supercurrent can be controlled by means of the field effect. 1,2 Gate-controlled superconductor/semiconductor hybrid devices such as superconducting field effect transistors 3 or split-gate structures 4 have been fabricated which find no counterpart in conventional SNS structures. In addition, the high carrier mobility attainable in semiconductors in combination with the phase-coherent Andreev reflection leads to novel unique phenomena in the magnetotransport. 5-7 Usually for these devices the semiconductor is patterned by conventional lithography. As an elegant alternative one can also directly create semiconductor nanostructures, i.e. nanowires, by epitaxial growth. 8 By using InAs nanowires connected to superconducting electrodes tunable Josephson supercurrents, supercurrent reversal, and Kondo-enhanced Andreev tunneling have been realized. [9][10][11] Among the various materials used for semiconductor nanowires InN is of particular interest for semiconductor/superconductor hybrid structures, since the surface accumulation layer in InN can provide a sufficiently low resistive contact to superconducting electrodes. 12-14 Due to almost ideal crystalline properties of InN nanowires electronic transport along the wires, contacted by normal metal electrodes, shows quantization phenomena, i.e. flux periodic magnetoconductance oscillations. 15 Furthermore, the carrier concentration in the surface electron gas is of the order of 10 13 cm −2 and thus about a factor of ten larger than in InAs. Consequently when combined with superconducting electrodes one can expect low resistive SNS junctions.Here, we report on transport studies of Nb/InNnanowire/Nb junctions. We succeeded in observing a pronounced Josephson supercurrent and a relatively large I c R N product of up to 0.44 mV. The latter factor, the critical current times the normal resistance, is an important figure of merit for Josephson junctions. We devoted special attention to the dependence of the critical current I c on an external magnetic field B, where a monotonous decrease of I c with B was found. This experimental finding is interpreted in the framework of a recent theoretical model for the proximity effect in narrow-width junctions with dimensions comparable or smaller than the magnetic length ξ B = Φ 0 /B,...

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“…In contrast to a superconductor-insulator-superconductor JJ, a proximity JJ of normal metal 52 , carbon nanotubes 21 , semiconducting nanowires 19 , or graphene 4 has negligibly small geometrical capacitance to allow hysteresis. In this analysis, we adopted the effective capacitance C eff originating from the diffusive nature of carriers in graphene, replacing the relaxation time R N C by the diffusion time of Andreev pairs 52 , h/E Th where E Th ¼ hD/L 2 is the Thouless energy (D ¼ v F l/2 is the diffusion constant in graphene, v F is the Fermi velocity, l is the mean free path and L is the junction length) 52 . G TA increases exponentially with temperature, which results in broadening of P(I c ) with increasing temperature.…”

Section: Methodsmentioning

confidence: 99%

Complete gate control of supercurrent in graphene p–n junctions

et al. 2013

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In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices.

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Proximity dc squids in the long-junction limit

Cited by 103 publications

References 49 publications

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Josephson supercurrent in Nb/InN-nanowire/Nb junctions

Complete gate control of supercurrent in graphene p–n junctions

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