Electronic transport transition at graphene/YBa2Cu3O7−δ junction

Sun, Qing; Wang, H. S.; Wang, H. M.; Deng, Lianwen; Hu, Zhaowen; Gao, Bo; Li, Q.; Xie, Xiaoming

doi:10.1063/1.4868118

Cited by 9 publications

(8 citation statements)

References 22 publications

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“…Instead, the cuprate film has to be epitaxially grown first on an appropriate substrate, for example, SrTiO 3 (STO), and then lithographic technique have been used to define the superconducting electrodes geometry, before a graphene sheet can be transferred onto them. Early attempts, by Sun et al, [131] Figure 8. STM studies of proximity induced superconductivity in graphene on top of a high-T C superconductor.…”

Section: Devices Based On D-wave Superconductors and Graphenementioning

confidence: 99%

Superconducting Proximity Effect in d‐Wave Cuprate/Graphene Heterostructures

et al. 2022

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Superconducting proximity effects in graphene have received a great deal of attention for over a decade now. This has unveiled a plethora of exotic effects linked to the specificities of graphene's electronic properties. The vast majority of the related studies are based on conventional, low-temperature superconducting metals with isotropic s-wave pairing. Here recent advances made on the less studied case of unconventional high-temperature superconducting cuprates are reviewed. These are characterized by an anisotropic d-wave pairing, whose interplay with Dirac electrons yields very rich physics and novel proximity behaviors. A theoretical analysis is provided and the experiments reported so far are summarized. These unveil hints of proximity-induced unconventional pairing and demonstrate the gate-tunable, long-range propagation of high-temperature superconducting correlations in graphene. Finally, the fundamental and technological opportunities brought by the theoretical and experimental advances are discussed, together with the interest in extending similar studies to other Dirac materials.

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Section: Devices Based On D-wave Superconductors and Graphenementioning

confidence: 99%

Superconducting Proximity Effect in d‐Wave Cuprate/Graphene Heterostructures

et al. 2022

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“…Fabricating YBCO/graphene devices with electron-transparent interfaces had remained challenging 17 . Contrary to low-temperature superconductors 2,4,11,[13][14][15][16][18][19][20] , YBCO cannot be grown on graphene due to its deposition conditions (hundreds of º C, oxygen-rich atmosphere).…”

mentioning

confidence: 99%

Tunable Klein-like tunnelling of high-temperature superconducting pairs into graphene

et al. 2017

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Superconductivity can be induced in a normal material via the 'leakage' of superconducting pairs of charge carriers from an adjacent superconductor. This so-called proximity e ect is markedly influenced by graphene's unique electronic structure, both in fundamental and technologically relevant ways. These include an unconventional form 1,2 of the 'leakage' mechanismthe Andreev reflection 3 -and the potential of supercurrent modulation through electrical gating 4 . Despite the interest of high-temperature superconductors in that context 5,6 , realizations have been exclusively based on low-temperature ones. Here we demonstrate a gate-tunable, high-temperature superconducting proximity e ect in graphene. Notably, gating e ects result from the perfect transmission of superconducting pairs across an energy barrier-a form of Klein tunnelling 7,8 , up to now observed only for non-superconducting carriers 9,10 -and quantum interferences controlled by graphene doping. Interestingly, we find that this type of interference becomes dominant without the need of ultraclean graphene, in stark contrast to the case of low-temperature superconductors 11 . These results pave the way to a new class of tunable, high-temperature Josephson devices based on large-scale graphene.Superconductivity is induced in a normal metal (N) in contact with a superconductor (S) via the Andreev reflection (AR) 3 : an electron entering S from N pairs to another electron to form a Cooper pair, leaving a hole-like quasiparticle that is transmitted back into N. Electron and hole coherently propagate with parallel opposite wavevectors, carrying superconducting correlations into N. This mechanism allows supercurrent flow and Josephson coupling across S-N-S junctions 12 .S-N proximity devices that can be greatly tuned by electrostatic doping are one of the main technological prospects of induced superconductivity in graphene 4,13-16 . Several specific mechanisms allow for that. Besides the density-of-states narrowing at the Dirac point, around which the junction's resistance increases, subtler effects may play a role. For example, the unusual possibility that the AR-involved electron and hole reside in different bandsconduction and valence-results in a specular Andreev reflection 1 (SAR) in which electron and hole wavevectors are mirror-like. SAR can occur if the graphene's Fermi energy E F is lower than the superconducting energy gap ∆, while for E F > ∆ the conventional (intra-band) AR takes place 1 . Thus, an AR to SAR crossover can be driven by shifting E F through a gate voltage, which dramatically changes the S-N interface conductance 2 .In the present experiments, tunability results from a different mechanism that involves Klein tunnelling-that is, the reflectionless transmission of electrons across a high energy barrier 7-10 . Beyond single electrons, here we observe Klein-like tunnelling of Andreev electron-hole pairs that carry superconducting correlations from the high-temperature superconductor YBa 2 Cu 3 O 7 (YBCO) into graphene. That effect i...

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“…SrTiO 3 (STO), and then lithographic technique have been used to define the superconducting electrodes' geometry, before a graphene sheet can be transferred onto them. Early attempts, by Sun et al [127], to implement such procedure via conventional photolithography and dry etching techniques to define the YBCO electrodes on which graphene was subsequently transferred, demonstrated that the cuprate/graphene interfaces obtained in that way generally presented very low transparency, thus precluding proximity effects. The experiment suggested that exposure of YBCO to chemicals and resists degrades its superconducting and normal-state properties on the c-axis surface, leading to an insulating layer.…”

Section: Devices Based On D-wave Superconductors and Graphenementioning

confidence: 99%

Superconducting proximity effect in $d$-wave cuprate/ graphene heterostructures

Perconte,

Bercioux,

Dlubak

et al. 2021

Preprint

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Superconducting proximity effects in graphene have received a great deal of attention for over a decade now. This has unveiled a plethora of exotic effects linked to the specificities of graphene's electronic properties. The vast majority of the related studies are based on conventional, low-temperature superconducting metals with isotropic s-wave pairing. Here we review recent advances made on the less studied case of unconventional high-temperature superconducting cuprates. These are characterized by an anisotropic d-wave pairing, whose interplay with Dirac electrons yields very rich physics and novel proximity behaviours. We provide a theoretical analysis and summarize the experiments reported so far. These unveil hints of proximity-induced unconventional pairing and demonstrate the gate-tunable, long-range propagation of high-temperature superconducting correlations in graphene. Finally, the fundamental and technological opportunities brought by the theoretical and experimental advances are discussed, together with the interest in extending similar studies to other Dirac materials.

show abstract

Electronic transport transition at graphene/YBa₂Cu₃O_7−δ junction

Cited by 9 publications

References 22 publications

Superconducting Proximity Effect in d‐Wave Cuprate/Graphene Heterostructures

Superconducting Proximity Effect in d‐Wave Cuprate/Graphene Heterostructures

Tunable Klein-like tunnelling of high-temperature superconducting pairs into graphene

Superconducting proximity effect in $d$-wave cuprate/ graphene heterostructures

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