Andreev-reflection in semiconductor-coupled superconducting weak-links

Kuhlmann, Matthias; Zimmermann, Uwe; Dikin, Dmitriy A.; Abens, S.; Keck, K.; Dmitriev, V. M.

doi:10.1007/bf01313010

Cited by 14 publications

(14 citation statements)

References 16 publications

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“…Using superconducting Al contacts on the Ge-Si nanowire, we will present the experimental observation of the dc Josephson effect: a finite switching current I SW through the nanowire Josephson junction. We will also look at multiple Andreev reflections (MAR) [57,58] and analyze the position of the resulting conductance peaks inside the superconducting gap of Al, ∆ Al . Additionally, we look at the temperature dependence of MARs and I SW and finally, we irradiate our junction with microwaves resulting in Shapiro steps, the first report on the ac Josephson effect in this system.…”

Section: Introductionmentioning

confidence: 99%

Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Ridderbos

Brauns

et al. 2019

Phys. Rev. Materials

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We present a Josephson junction based on a Ge-Si core-shell nanowire with transparent superconducting Al contacts, a building block which could be of considerable interest for investigating Majorana bound states, superconducting qubits and Andreev (spin) qubits. We demonstrate the dc Josephson effect in the form of a finite supercurrent through the junction, and establish the ac Josephson effect by showing up to 23 Shapiro steps. We observe multiple Andreev reflections up to the sixth order, indicating that charges can scatter elastically many times inside our junction, and that our interfaces between superconductor and semiconductor are transparent and have low disorder. arXiv:1908.07579v1 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Ridderbos

Brauns

et al. 2019

Phys. Rev. Materials

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“…In particular, its extension to the experimentally relevant situation of asymmetric junctions was developed and applied in Refs. [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

Analytical calculation of the excess current in the Octavio–Tinkham–Blonder–Klapwijk theory

Niebler

Cuniberti

Novotný

2009

Supercond. Sci. Technol.

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We present an analytical derivation of the excess current in Josephson junctions within the Octavio-Tinkham-Blonder-Klapwijk theory for both symmetric and asymmetric barrier strengths. We confirm the result found numerically by Flensberg et al. for equal barriers [Physical Review B 38, 8707 (1988)], including the prediction of negative excess current for low transparencies, and we generalize it for differing barriers. Our analytical formulae provide for convenient fitting of experimental data, also in the less studied, but practically relevant case of the barrier asymmetry.

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“…1 and 2 for N = 1, 2, 3 perfectly. To the best of our knowledge, this is the first observation in nanowire-based devices of subharmonic structures where different gaps are involved, after the early investigations in planar Pb/InSb/Sn junctions 26,48 . In Fig.…”

mentioning

confidence: 73%

“…3C favour multiple Andreev processes at energies that relate to both gaps in a particular way. Odd orders manifest as conductance peaks at subharmonic values of the sum of the two gaps 26,48 :…”

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confidence: 99%

Single-shot fabrication of semiconducting-superconducting nanowire devices

Borsoi,

Mazur,

van Loo

et al. 2020

Preprint

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Semiconducting-superconducting nanowires attract widespread interest owing to the possible presence of non-abelian Majorana zero modes, which hold promise for topological quantum computation. However, the search for Majorana signatures is challenging because reproducible hybrid devices with desired nanowire lengths and material parameters need to be reliably fabricated to perform systematic explorations in gate voltages and magnetic fields. Here, we exploit a fabrication platform based on shadow walls that enables the in-situ, selective and consecutive depositions of superconductors and normal metals to form normal-superconducting junctions.Crucially, this method allows to realize devices in a single shot, eliminating fabrication steps after the synthesis of the fragile semiconductor/superconductor interface. At the atomic level, all investigated devices reveal a sharp and defect-free semiconducting-superconducting interface and, correspondingly, we measure electrically a hard induced superconducting gap. While our advancement is of crucial importance for enhancing the yield of complex hybrid devices, it also offers a straightforward route to explore new material combinations for hybrid devices.

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Andreev-reflection in semiconductor-coupled superconducting weak-links

Cited by 14 publications

References 16 publications

Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Multiple Andreev reflections and Shapiro steps in a Ge-Si nanowire Josephson junction

Analytical calculation of the excess current in the Octavio–Tinkham–Blonder–Klapwijk theory

Single-shot fabrication of semiconducting-superconducting nanowire devices

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