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Your search keyword '"Guéron, S."' showing total 23 results
Start Over Author "Guéron, S." Journal physical review b
23 results on '"Guéron, S."'

7. Magnetic field resistant quantum interferences in Josephson junctions based on bismuth nanowires

Author

Li, Chuan, primary, Kasumov, A., additional, Murani, Anil, additional, Sengupta, Shamashis, additional, Fortuna, F., additional, Napolskii, K., additional, Koshkodaev, D., additional, Tsirlina, G., additional, Kasumov, Y., additional, Khodos, I., additional, Deblock, R., additional, Ferrier, M., additional, Guéron, S., additional, and Bouchiat, H., additional

Published
2014
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19. Proximity effect in a superconductor-metallofullerene-superconductor molecular junction

Author

Kasumov, A. Yu., primary, Tsukagoshi, K., additional, Kawamura, M., additional, Kobayashi, T., additional, Aoyagi, Y., additional, Senba, K., additional, Kodama, T., additional, Nishikawa, H., additional, Ikemoto, I., additional, Kikuchi, K., additional, Volkov, V. T., additional, Kasumov, Yu. A., additional, Deblock, R., additional, Guéron, S., additional, and Bouchiat, H., additional

Published
2005
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22. Full range of proximity effect probed with superconductor/graphene/superconductor junctions.

Author

Chuan Li, Guéron, S., Chepelianskii, A., and Bouchiat, H.

Subjects
*GRAPHENE, *QUANTUM Hall effect, *SUPERCONDUCTORS, *ELECTRODES, *NUMERICAL analysis
Abstract

The high tunability of the density of states of graphene makes it an ideal probe of quantum transport in different regimes. In particular, the supercurrent that can flow through a nonsuperconducting (N) material connected to two superconducting (S) electrodes, crucially depends on the length of the N relative to the superconducting coherence length. Using graphene as the N material we have investigated the full range of the superconducting proximity effect, from short to long diffusive junctions. By combining several S/graphene/S samples with different contacts and lengths, and measuring their gate-dependent critical currents (Ic) and normal state resistance RN, we compare the product eRNIc to the relevant energies, the Thouless energy in long junctions and the superconducting gap of the contacts in short junctions, over three orders of magnitude of Thouless energy. The experimental variations strikingly follow a universal law, close to the predictions of the proximity effect both in the long and short junction regime, as well as in the crossover region, thereby revealing the interplay of the different energy scales. Differences in the numerical coefficients reveal the crucial role played by the interfacial barrier between graphene and the superconducting electrodes, which reduces the supercurrent in both short and long junctions. Surprisingly, the reduction of supercurrent is independent of the gate voltage and of the nature of the electrodes. A reduced induced gap and Thouless energy are extracted, revealing the role played by the dwell time in the barrier in the short junction, and an effective increased diffusion time in the long junction. We compare our results to the theoretical predictions of Usadel equations and numerical simulations, which better reproduce experiments with imperfect NS interfaces. [ABSTRACT FROM AUTHOR]

Published
2016
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23. Signature of gate-tunable magnetism in graphene grafted with Pt-porphyrins.

Author

Chuan Li, Komatsu, Katsuyoshi, Bertrand, S., Clavé, G., Campidelli, S., Filoramo, A., Guéron, S., and Bouchiat, H.

Subjects
*MAGNETISM, *PLATINUM compounds, *GRAPHENE, *PORPHYRINS, *EXCHANGE interactions (Magnetism), *ELECTRODES
Abstract

Inducing magnetism in graphene holds great promises, such as controlling the exchange interaction with a gate electrode, and generating exotic magnetic phases. Coating graphene with magnetic molecules or atoms has so far mostly led to decreased graphene mobility. In the present work, we show that Pt-porphyrin molecules adsorbed on graphene lead both to an enhanced mobility, and to gate-dependent magnetism. We report that porphyrins can act both as donor or acceptor molecules, depending on the initial doping of the graphene sheet. The porphyrins transfer charge and ionize around the charged impurities on graphene, and, consequently, the graphene doping is decreased and its mobility is enhanced. In addition, ionized porphyrin molecules carry a magnetic moment. Using the sensitivity of mesoscopic transport to magnetism, in particular, the superconducting proximity effect and conductance fluctuations, we explore the magnetic order induced in graphene by the interacting magnetic moments of the ionized porphyrin molecules. Among the signatures of magnetism, we find two-terminal-magnetoresistance fluctuations with an odd component, a tell-tale sign of time-reversal symmetry breaking at zero field, which does not exist in uncoated graphene samples. When graphene is connected to superconducting electrodes, the induced magnetism leads to a gate-voltage-dependent suppression of the supercurrent, modified magnetic interference patterns, and gate-voltage-dependent magnetic hysteresis. The magnetic signatures are greatest for long superconductor/graphene/superconductor junctions, and for samples with the highest initial doping, compatible with a greater number of ionized, and thus magnetic porphyrin molecules. Our findings suggest that long-range (of the order of the coherence length, or micrometers) magnetism is induced through graphene by the ionized porphyrins' magnetic moment. This magnetic interaction is controled by the density of carriers in graphene, a tunability that could be exploited in spintronic applications. [ABSTRACT FROM AUTHOR]

Published
2016
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