Observation of supercurrent in PbIn-graphene-PbIn Josephson junction

Jeong, Dongchan; Choi, Jaehyun; Lee, Gil‐Ho; Jo, Sanghyun; Doh, Yong-Joo; Lee, Hu-Jong

doi:10.1103/physrevb.83.094503

Cited by 73 publications

(106 citation statements)

References 37 publications

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“…2a for a fixed microwave power (P). Figure 2a clearly shows that the SSs are absent near the CNP, in contrast to the previous report of significantly reduced but still finite SSs in the plain JJG 11 . The vanishing SSs are attributed to complete I c suppression at the CNP in this experiment.…”

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confidence: 54%

“…As our bipolar JJG exhibits the maximum I c R n ¼ 40 mV in the overdoped region, the minimum I c is expected to be B44 nA from R n ¼ 450 O at the CNP. This discrepancy, between the expected value of I c and the observed completely suppressed value, is not explained by thermal fluctuations 11 . Thermal suppression of I c by 2 nA is estimated for T ¼ 50 mK, by comparing the Josephson coupling energy (E J ¼ :I c /2e; : ¼ h/2p) and thermal energy 14 (k B T).…”

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confidence: 86%

“…In this case, the I c R n product is nearly constant as B2D/e with V bg in a ballistic short junction 13 , which is in essence the Ambegaokar-Baratoff relation 14 ; in a diffusive long junction, it is given by aE Th /e (refs 11,27), where E Th is the Thouless energy and a is a coefficient depending on E Th /D. Previous experiments 4,9-11 of JJG in a diffusive junction regime have shown that the I c R n product at the CNP is almost half the maximum value obtained in the overdoped region.…”

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confidence: 99%

“…In a JJG, however, complete switching off of the junction supercurrent by the gate voltages has not yet been achieved. This incomplete gate control of the supercurrent in a JJG 4,[9][10][11] poses an obstacle in the way of quantum-state engineering.…”

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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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confidence: 86%

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confidence: 99%

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Complete gate control of supercurrent in graphene p–n junctions

et al. 2013

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“…To our knowledge Pb has not been used previously in InAs or any NW Josephson junctions, though a dilute PbIn compound and Pb have proved to be a suitable candidates for Josephson junctions using graphene as a weak link [19,20]. The high critical temperature of Pb combined with the ease of evaporation makes it a promising and solid alternative to superconducting Nb as a contact electrode material.…”

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confidence: 99%

Pb/InAs Nanowire Josephson Junction with High Critical Current and Magnetic Flux Focusing

et al. 2015

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We have studied mesoscopic Josephson junctions formed by highly n-doped InAs nanowires and superconducting Ti/Pb source and drain leads. The current-voltage properties of the system are investigated by varying temperature and external out-of-plane magnetic field. Superconductivity in the Pb electrodes persists up to ∼ 7 K and with magnetic field values up to 0.4 T. Josephson coupling at zero backgate voltage is observed up to 4.5 K and the critical current is measured to be as high as 615 nA. The supercurrent suppression as a function of the magnetic field reveals a diffraction pattern that is explained by a strong magnetic flux focusing provided by the superconducting electrodes forming the junction.

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Quantum Transport in Graphene: Impurity Scattering as a Probe of the Dirac Spectrum

Guéron

Bouchiat

2017

Progress in Mathematical Physics

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Abstract. Since the very first investigations of the electronic properties of graphene, the nature of the scattering disorder potential has been shown to play an essential role in determining the carrier density dependence of the conductance. Impurity scattering is characterized by two different times the transport and elastic scattering times which are sensitive to the particular Dirac spectrum of graphene. The analysis of the ratio between these two times gives insight on the nature (neutral or charged) and range of the scatterers. We show how to extract these two times from magneto-transport measurements and analyze their differences in monolayer and bilayer Graphene in relation with the different symmetry properties of their band structure and wave functions. It is found that whereas short range impurity scattering is the dominant mechanism limiting the classical transport, phase coherent mesoscopic transport is very sensitive to long range disorder. In particular, the formation of electron/hole puddles in the vicinity of the charge neutrality point strongly affects the transport of Andreev pairs in the presence of superconducting electrodes. We will also discuss the modification of electronic properties of graphene in the presence of adsorbed atoms and molecules and in particular focus on spin dependent scattering on adsorbates leading to a spin orbit interaction. There is indeed a big interest in controlling and inducing spin orbit interactions in graphene. One can hope to induce and detect a spin Hall effect with a great potential impact in graphene based spintronic devices and ultimately reach a regime of quantum spin Hall physics. In contrast with these very short range scatterers, we discuss the possibility to engineer networks of larger range strained regions in which electronic properties are locally modified by transferring graphene on arrays of silicon oxyde nanopillars.

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Observation of supercurrent in PbIn-graphene-PbIn Josephson junction

Cited by 73 publications

References 37 publications

Complete gate control of supercurrent in graphene p–n junctions

Complete gate control of supercurrent in graphene p–n junctions

Pb/InAs Nanowire Josephson Junction with High Critical Current and Magnetic Flux Focusing

Quantum Transport in Graphene: Impurity Scattering as a Probe of the Dirac Spectrum

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