DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions

Talantsev, E. F.

doi:10.3390/nano9111554

Cited by 5 publications

(4 citation statements)

References 65 publications

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“…As Raman spectroscopy experiments have revealed, BLG systems can support two phonon modes [5][6][7][8][9][10][11][12][13][14][15], one corresponding to intralayer vibrations and the other to interlayer vibrations. In this spirit, a two-gap superconductivity has been proposed and studied for displaced and commensurate twisted BLG systems [53,56,57]. It was found that, depending on the original stacking order of BLG (being either AA or AB) and the magnitude of the chemical potential, a small in-plane displacement of the pristine layers with respect to each other can drive s-wave and p-wave pairing symmetries into d-wave and f -wave symmetry classes, respectively, and increase the superconducting critical temperature [53].…”

mentioning

confidence: 99%

Josephson effect in graphene bilayers with adjustable relative displacement

Alidoust

Jauho

Akola

2020

Phys. Rev. Research

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The Josephson current is investigated in a superconducting graphene bilayer where pristine graphene sheets can make in-plane or out-of-plane displacements with respect to each other. The superconductivity can be of an intrinsic nature, or due to a proximity effect. The results demonstrate that the supercurrent responds qualitatively differently to relative displacement if the superconductivity is due to either intralayer or interlayer spin-singlet electron-electron pairing, thus providing a tool to distinguish between the two mechanisms. Specifically, both the AA and AB stacking orders are studied with antiferromagnetic spin alignment. For the AA stacking order with intralayer and on-site pairing no current reversal is found. In contrast, the supercurrent may switch its direction as a function of the in-plane displacement and out-of-plane interlayer coupling for the cases of AA ordering with interlayer pairing and AB ordering with either intralayer or interlayer pairing. In addition to sign reversal, the Josephson signal displays many characteristic fingerprints which derive directly from the pairing mechanism. Thus, measurements of the Josephson current as a function of the graphene bilayer displacement open up the means to achieve deeper insights into the superconducting pairing mechanism.

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confidence: 99%

Josephson effect in graphene bilayers with adjustable relative displacement

Alidoust

Jauho

Akola

2020

Phys. Rev. Research

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“…13,14). It is interesting to note that in our previous papers [17,[32][33][34] we found that many atomically thin superconductors, including SLG and topological insulators (with a proximity induced superconducting state) have a two-superconducting band state.…”

Section: Figurementioning

confidence: 69%

Classifying superconductivity in Moiré graphene superlattices

Talantsev

Mataira

Crump

2020

Sci Rep

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Several research groups have reported on the observation of superconductivity in bilayer graphene structures where single atomic layers of graphene are stacked and then twisted at angles forming Moiré superlattices. The characterization of the superconducting state in these 2D materials is an ongoing task. Here we investigate the pairing symmetry of bilayer graphene Moiré superlattices twisted at  = 1.05°, 1.10° and 1.16° for carrier doping states varied in the range of = 0.5 − 1.5 • 10 12 −2 (where superconductivity can be realized) by analyzing the temperature dependence of the upper critical field Bc2(T) and the self-field critical current Jc(sf,T) within currently available models for single-and two-band s-, d-, pand d+id-wave gap symmetries. Extracted superconducting parameters show that only s-wave and a specific kind of p-wave symmetries are likely to be dominant in bilayer graphene Moiré superlattices. More experimental data is required to distinguish between the s-and remaining p-wave symmetries as well as the suspected two-band superconductivity in these 2D superlattices.

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“…Figures 5d-f present the analysis of Talantsev et al concerning the superconduting parameters of tBLG samples. The superconducting parameters were derived from fits to the data of the upper critical field, H c2 (T) and the critical current density, J c (T)(self field), following the models by [91][92][93][94][95][96][97][98][99]. All this gives valuable information on the properties of the superconducting state(s) in tBLG samples.…”

Section: Phase Diagrams Of Moiré Superconductors and Comparison With ...mentioning

confidence: 99%

Moiré Superconductivity and the Roeser-Huber Formula

Koblischka¹,

Koblischka-Veneva²

2023

Preprint

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As shown previously, a relation between the superconducting transition temperature and some characteristic distance in the crystal lattice holds, which enables the calculation of the superconducting transition temperature, Tc, based only on the knowledge of the electronic configuration and of some details of the crystallographic structure. This relation was found to apply for a large number of superconductors, including the high-temperature superconductors, the iron-based materials, alkali fullerides, metallic alloys, and element superconductors. When applying this scheme called Roeser-Huber formula to Moiré-type superconductivity, i.e., magic-angle twisted bi-layer graphene (tBLG) and bi-layer WSe2, we find that the calculated transition temperatures for tBLG are always higher than the available experimental data, e.g., for the magic angle 1.1∘, we find Tc≈ 4.2–6.7 K. Now, the question arises why the calculation produces larger Tc’s. Two possible scenarios may answer this question: (1) The given problem for experimentalists is the fact that for electric measurements always substrates/caps are required to arrange the electric contacts. When now discussing superconductivity in atomically thin objects, also these layers may play a role forming the Moiré patterns. The consequence of such substrate-induced super-Moiré patterns is that the resulting Moiré pattern always will show a larger cell size, and thus, a lower Tc of the final structure will result. (2) A correction factor to the Roeser-Huber formalism may be required to account for the low charge carrier density of the tBLG. Here, we test both scenarios and find that the introduction of a correction factor η enables a proper calculation of Tc, reproducing the experimental data. We find that η depends exponentially on the value of Tc.

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DC Self-Field Critical Current in Superconductor/Dirac-Cone Material/Superconductor Junctions

Cited by 5 publications

References 65 publications

Josephson effect in graphene bilayers with adjustable relative displacement

Josephson effect in graphene bilayers with adjustable relative displacement

Classifying superconductivity in Moiré graphene superlattices

Moiré Superconductivity and the Roeser-Huber Formula

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