Hysteretic Critical State in Coplanar Josephson Junction with Monolayer Graphene Barrier

  • D. Massarotti
  • B. Jouault
  • V. Rouco
  • G. Campagnano
  • D. Giuliano
  • P. Lucignano
  • D. Stornaiuolo
  • G. P. Pepe
  • F. Lombardi
  • F. Tafuri
  • A. Tagliacozzo


Coplanar Al/graphene/Al junctions fabricated on the same graphene sheet deposited on silicon carbide (SiC), show robust Josephson coupling at subKelvin temperature, when the separations between the electrodes is below 400 nm. Remarkably, a hysteretic Critical State sets in when ramping an orthogonal magnetic field, with a sudden collapse of the Josephson critical current Ic when turning the field on, and a revival of Ic when inverting the sweep. Similar hysteresis can be found in granular superconducting films which may undergo the Berezinskii-Kosterlitz-Thouless transition. Here, we give quantitative arguments to prove that this odd behavior of the magnetoconductance gives evidence for an incipient Berezinskii-Kosterlitz-Thouless transition with drift and pinning of fluctuating free vortices induced by the current bias.


Graphene Josephson effect Silicon carbide 



The authors thank the Swedish Foundation for Strategic Research (SSF) under the project “Graphene based high frequency electronics” at Chalmers, where the samples were patterned and the collaboration of S. Charpentier and T. Bauch. Discussions with L. Benfatto, V.Bouchiat, P. Brouwer and Ya.V. Kopelevich are gratefully acknowledged. Work supported by PICS CNRS-CNR 2014-2016 “Transport phenomena and Proximity-induced Superconductivity in Graphene junctions,” FIRB “HybridNanoDev” RBFR1236VV (Italy) and by EU FP7, under grant agreement no 604391 Graphene Flagship.


  1. 1.
    Ojeda-Aristizabal, C., Ferrier, M., Guéron, S., Bouchiat, H.: Tuning the proximity effect in a superconductorgraphene- superconductor junction. Phys. Rev. B 79, 165436 (2009)ADSCrossRefGoogle Scholar
  2. 2.
    Mizuno, N., Nielsen, B., Du, X.: Ballistic-like supercurrent in suspended graphene Josephson weak links. Nat. Commun. 4, 2716 (2013)ADSCrossRefGoogle Scholar
  3. 3.
    Baringhaus, J., Ruan, M., Edler, F., Tejeda, A., Sicot, M., Taleb-Ibrahimi, A., Li, A. P., Jiang, Z. G., Conrad, E. H., Berger, C., Tegenkamp, C., de Heer, W. A.: Exceptional ballistic transport in epitaxial graphene nanoribbons. Nature 506(7488), 349 (2014)ADSCrossRefGoogle Scholar
  4. 4.
    Calado, V. E., Goswami, S., Nanda, G., Diez, M., Akhmerov, A. R., Watanabe, K., Taniguchi, T., Klapwijk, T. M., Vandersypen, L. M. K.: Ballistic Josephson junctions in edge-contacted graphene. Nat. Nanotechnol. 10(9), 761 (2015)ADSCrossRefGoogle Scholar
  5. 5.
    Ben Shalom, M., Zhu, M. J., Fal’ko, V. I., Mishchenko, A., Kretinin, A. V., Novoselov, K. S., Woods, C. R., Watanabe, K., Taniguchi, T., Geim, A. K., Prance, J.R.: Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene. Nat. Phys. 12(4), 318 (2016)CrossRefGoogle Scholar
  6. 6.
    Beenakker, C. W. J.: Specular Andreev Reflection in Graphene. Phys. Rev. Lett. 97, 067007 (2006)ADSCrossRefGoogle Scholar
  7. 7.
    Titov, M., Ossipov, A., Beenakker, C. W. J.: Excitation gap of a graphene channel with superconducting boundaries. Phys. Rev. B 75, 045417 (2007)ADSCrossRefGoogle Scholar
  8. 8.
    Heersche, H. B., Jarillo-Herrero, P., Oostinga, J. B., Vandersypen, L. M. K., Morpurgo, A. F.: Bipolar supercurrent in graphene. Nature 446(7131), 56 (2007)ADSCrossRefGoogle Scholar
  9. 9.
    Deon, F., Šopić, S., Morpurgo, A.F.: Tuning the Influence of Microscopic Decoherence on the Superconducting Proximity Effect in a Graphene Andreev Interferometer. Phys. Rev. Lett. 112, 126803 (2014)ADSCrossRefGoogle Scholar
  10. 10.
    Choi, J. -H., Lee, G. -H., Park, S., Jeong, D., Lee, J. -O., Sim, H. S., Doh, Y. -J., Lee, H. -J.: Complete gate control of supercurrent in graphene p-n junctions. Nat. Commun. 4, 2525 (2013)ADSGoogle Scholar
  11. 11.
    Dirks, T., Hughes, T. L., Lal, S., Uchoa, B., Chen, Y. F., Chialvo, C., Goldbart, P. M., Mason, N.: Transport through Andreev bound states in a graphene quantum dot. Nat. Phys. 7(5), 386 (2011)CrossRefGoogle Scholar
  12. 12.
    Kedzierski, J., Hsu, P. -L., Healey, P., Wyatt, P. W., Keast, C. L., Sprinkle, M., Berger, C., de Heer, W. A.: IEEE Trans. Electron Devices 55(8), 2078 (2008)ADSCrossRefGoogle Scholar
  13. 13.
    Lee, G. H., Kim, S., Jhi, S. H., Lee, H. J.: Ultimately short ballistic vertical graphene Josephson junctions. Nat. Commun. 6, 6181 (2015)ADSCrossRefGoogle Scholar
  14. 14.
    Heersche, H. B., Jarillo-Herrero, P., Oostinga, J. B., Vandersypen, L. M. K., Morpurgo, A. F.: Induced superconductivity in graphene. Solid State Commun. 143(1–2), 72 (2007)ADSCrossRefGoogle Scholar
  15. 15.
    Du, X., Skachko, I., Andrei, E. Y.: Josephson current and multiple Andreev reflections in graphene SNS junctions. Phys. Rev. B 77, 184507 (2008)ADSCrossRefGoogle Scholar
  16. 16.
    Borzenets, I. V., Coskun, U. C., Jones, S. J., Finkelstein, G.: Phase Diffusion in Graphene-Based Josephson Junctions. Phys. Rev. Lett. 107(13), 137005 (2011)ADSCrossRefGoogle Scholar
  17. 17.
    Lee, G.-H., Jeong, D., Choi, J.-H., Doh, Y.-J., Lee, H.-J.: Electrically Tunable Macroscopic Quantum Tunneling in a Graphene-Based Josephson Junction. Phys. Rev. Lett. 107(14), 146605 (2011)ADSCrossRefGoogle Scholar
  18. 18.
    Popinciuc, M., Calado, V. E., Liu, X. L., Akhmerov, A. R., Klapwijk, T. M., Vandersypen, L. M. K.: Zero-bias conductance peak and Josephson effect in graphene-NbTiN junctions. Phys. Rev. B 85(20), 205404 (2012)ADSCrossRefGoogle Scholar
  19. 19.
    Coskun, U. C., Brenner, M., Hymel, T., Vakaryuk, V., Levchenko, A., Bezryadin, A.: Phys. Rev. Lett. 108(9), 097003 (2012)ADSCrossRefGoogle Scholar
  20. 20.
    Lafont, F., Ribeiro-Palau, R., Kazazis, D., Michon, A., Couturaud, O., Consejo, C., Chassagne, T., Zielinski, M., Portail, M., Jouault, B., Schopfer, F., Poirier, W.: Quantum Hall resistance standards from graphene grown by chemical vapour deposition on silicon carbide. Nat. Commun. 6, 6806 (2015)ADSCrossRefGoogle Scholar
  21. 21.
    Ribeiro Palau, R., Lafont, F., Brun Picard, J., Kazazis, D., Michon, A., Cheynis, F., Couturaud, O., Consejo, C., Jouault, B., Poirier, W., Schopfer, F.: Quantum Hall resistance standard in graphene devices under relaxed experimental conditions. Nat. Nanotechnol. 10(11), 965 (2015)ADSCrossRefGoogle Scholar
  22. 22.
    Li, X. S., Cai, W. W., An, J. H., Kim, S., Nah, J., Yang, D. X., Piner, R., Velamakanni, A., Jung, I., Tutuc, E., Banerjee, S. K., Colombo, L., Ruoff, R. S.: Large-area synthesis of high-quality and uniform graphene films on copper foils. Science 324(5932), 1312 (2009)ADSCrossRefGoogle Scholar
  23. 23.
    Poirier, W., Lafont, F., Djordjevic, S., Schopfer, F., Devoille, L.: A programmable quantum current standard from the Josephson and the quantum Hall effects. J. Appl. Phys. 115(4), 044509 (2014)ADSCrossRefGoogle Scholar
  24. 24.
    Komatsu, K., Li, C., Autier-Laurent, S., Bouchiat, H., Guéron, S.: Superconducting proximity effect in long superconductor/graphene/superconductor junctions: From specular Andreev reflection at zero field to the quantum Hall regime. Phys. Rev. B 86, 115412 (Sep 2012)Google Scholar
  25. 25.
    Black-Schaffer, A. M., Doniach, S.: Resonating valence bonds and mean-field d-wave superconductivity in graphite. Phys. Rev. B 75, 134512 (Apr 2007)Google Scholar
  26. 26.
    Nandkishore, R., Levitov, L. S., Chubukov, A. V.: Superconducting states of pure and doped graphene. Nat. Phys. 8, 158 (2012)CrossRefGoogle Scholar
  27. 27.
    Uchoa, B., Castro Neto, A. H.: Superconducting states of pure and doped graphene. Phys. Rev. Lett. 98, 146801 (2007)ADSCrossRefGoogle Scholar
  28. 28.
    Allain, A., Han, Z., Bouchiat, V.: Superconducting states of pure and doped graphene. Nat. Mater. 11, 590 (2012)ADSCrossRefGoogle Scholar
  29. 29.
    Li, K., Feng, X., Zhang, W., Ou, Y., Chen, L., He, K., Wang, L.-L., Guo, L., Liu, G., Xue, Q.-K., Ma, X.: Superconductivity in Ca-intercalated epitaxial graphene on silicon carbide. Appl. Phys. Lett. 103(6), 062601 (2013)ADSCrossRefGoogle Scholar
  30. 30.
    Ludbrook, B. M., Levy, G., Nigge, P., Zonno, M., Schneider, M., Dvorak, D. J., Veenstra, C. N., Zhdanovich, S., Wong, D., Dosanjh, P., Straßer, C., Stöhr, A., Forti, S., Ast, C. R., Starke, U., Damascelli, A.: Evidence for superconductivity in Lidecorated monolayer graphene. Proc. Natl. Acad. Sci. 112(38), 11795 (2015)ADSCrossRefGoogle Scholar
  31. 31.
    Tiwari, A. P., Shin, S., Hwang, E., Jung, S. -G., Park, T., Lee, H.: Superconductivity at 7.4 K in Few Layer Graphene by Li-intercalation. ArXiv e-prints (2015)Google Scholar
  32. 32.
    Han, Z., Allain, A., Arjmandi-Tash, H., Tikhonov, K., Feigel’man, M., Sacepe, B., Bouchiat, V.: Collapse of superconductivity in a hybrid tin-graphene Josephson junction array. Nat. Phys. 10(5), 380 (2014)CrossRefGoogle Scholar
  33. 33.
    Massarotti, D., Jouault, B., Rouco, V., Charpentier, S., Bauch, T., Michon, A., De Candia, A., Lucignano, P., Lombardi, F., Tafuri, F., Tagliacozzo, A.: Incipient berezinskii-kosterlitz-thouless transition in two-dimensional coplanar josephson junctions. Phys. Rev. B 94, 054525 (2016)ADSCrossRefGoogle Scholar
  34. 34.
    Tinkham, M.: Introduction to Superconductivity. McGraw-Hill, Singapore (1996)Google Scholar
  35. 35.
    Palau, A., Puig, T., Obradors, X., Pardo, E., Navau, C., Sanchez, A., Usoskin, A., Freyhardt, H. C., Fernández, L., Holzapfel, B., Feenstra, R.: Simultaneous inductive determination of grain and intergrain critical current densities of YBa2Cu3O7 coated conductors. Appl. Phys. Lett. 84(2), 230 (2004)ADSCrossRefGoogle Scholar
  36. 36.
    Palau, A., Puig, T., Obradors, X., Jooss, C.: Simultaneous determination of grain and grain-boundary critical currents in YBa2Cu3O7-coated conductors by magnetic measurements. Phys. Rev. B 75, 054517 (2007)ADSCrossRefGoogle Scholar
  37. 37.
    Ji, L., Rzchowski, M. S., Anand, N., Tinkham, M.: Magnetic-field-dependent surface resistance and two-level critical-state model for granular superconductors. Phys. Rev. B 47, 470–483 (1993)ADSCrossRefGoogle Scholar
  38. 38.
    José, J. V.: 40 Years of Berezinskii-Kosterlitz-Thouless Theory. World Scientific, Singapore (2013)CrossRefMATHGoogle Scholar
  39. 39.
    Jabakhanji, B., Michon, A., Consejo, C., Desrat, W., Portail, M., Tiberj, A., Paillet, M., Zahab, A., Cheynis, F., Lafont, F., Schopfer, F., Poirier, W., Bertran, F., Le Fèvre, P., Taleb-Ibrahimi, A., Kazazis, D., Escoffier, W., Camargo, B. C., Kopelevich, Y., Camassel, J., Jouault, B.: Tuning the transport properties of graphene films grown by CVD on SiC(0001): Effect of in situ hydrogenation and annealing. Phys. Rev. B 89, 085422 (2014)ADSCrossRefGoogle Scholar
  40. 40.
    Jouault, B., Charpentier, S., Massarotti, D., Michon, A., Paillet, M., Huntzinger, J. R., Tiberj, A., Zahab, A. -A., Bauch, T., Lucignano, P., Tagliacozzo, A., Lombardi, F., Tafuri, F.: Josephson coupling in junctions made of monolayer graphene grown on SiC. J. Supercond. Nov. Magn. 29(5), 1145–1150 (2016)CrossRefGoogle Scholar
  41. 41.
    Tanabe, S., Sekine, Y., Kageshima, H., Nagase, M., Hibino, H.: Carrier transport mechanism in graphene on SiC(0001). Phys. Rev. B 84, 115458 (2011)ADSCrossRefGoogle Scholar
  42. 42.
    Speck, F., Jobst, J., Fromm, F., Ostler, M., Waldmann, D., Hundhausen, M., Weber, H.B., Seyller, T.: The quasifree- standing nature of graphene on H-saturated SiC(0001). Appl. Phys. Lett. 99(12), 122106 (2011)ADSCrossRefGoogle Scholar
  43. 43.
    Miao, F., Bao, W., Zhang, H., Lau, C. N.: Premature switching in graphene Josephson transistors. Solid State Commun. 149(27–28), 1046 (2009)ADSCrossRefGoogle Scholar
  44. 44.
    Larkin, T. I., Bol’ginov, V. V., Stolyarov, V. S., Ryazanov, V. V., Vernik, I. V., Tolpygo, S. K., Mukhanov, O. A.: Ferromagnetic Josephson switching device with high characteristic voltage. Appl. Phys. Lett. 100(22) (2012)Google Scholar
  45. 45.
    Ishii, C.: Josephson currents through junctions with normal metal barriers. Prog. Theor. Phys. 44(6), 1525–1547 (1970)ADSCrossRefGoogle Scholar
  46. 46.
    Giuliano, D., Affleck, I.: The josephson current through a long quantum wire. J. Stat. Mech. Theory Exper. 2013(02), P02034 (2013)MathSciNetCrossRefGoogle Scholar
  47. 47.
    Jeong, D., Choi, J. -H., Lee, G. -H., Jo, S., Doh, Y. -J., Lee, H. -J.: Observation of supercurrent in PbIn-graphene-PbIn Josephson junction. Phys. Rev. B 83, 094503 (2011)ADSCrossRefGoogle Scholar
  48. 48.
    Wu, Y., Perebeinos, V., Lin, Y. M., Low, T., Xia, F., Avouris, P.: Quantum Behavior of Graphene Transistors near the Scaling Limit. Nano Lett. 12(3), 1417 (2012)ADSCrossRefGoogle Scholar
  49. 49.
    Giovannetti, G., Khomyakov, P. A., Brocks, G., Karpan, V. M., van den Brink, J., Kelly, P. J.: Doping Graphene with Metal Contacts. Phys. Rev. Lett. 101, 026803 (2008)ADSCrossRefGoogle Scholar
  50. 50.
    Cheianov, V. V., Fal’ko, V. I.: Selective transmission of Dirac electrons and ballistic magnetoresistance of np junctions in graphene. Phys. Rev. B 74, 041403 (2006)ADSCrossRefGoogle Scholar
  51. 51.
    Rosenthal, P. A., Beasley, M. R., Char, K., Colclough, M. S., Zaharchuk, G.: Flux focusing effects in planar thinfilm grainboundary Josephson junctions. Appl. Phys. Lett. 59(26), 3482 (1991)ADSCrossRefGoogle Scholar
  52. 52.
    Tafuri, F., Kirtley, J. R.: Rep. Prog. Phys. 68(11), 2573 (2005)ADSCrossRefGoogle Scholar
  53. 53.
    Arpaia, R., Arzeo, M., Nawaz, S., Charpentier, S., Lombardi, F., Bauch, T.: Ultra low noise YBa2Cu3O7 δ nano superconducting quantum interference devices implementing nanowires. Appl. Phys. Lett. 104(7), 072603 (2014)ADSCrossRefGoogle Scholar
  54. 54.
    De Gennes, P. G.: Superconductivity of Metals and Alloys. Advanced Book Classics. Perseus, Cambridge (1999)Google Scholar
  55. 55.
    Bean, C. P., Livingston, J. D.: Surface barrier in type-II superconductors. Phys. Rev. Lett. 12, 14 (1964)ADSCrossRefGoogle Scholar
  56. 56.
    Aladyshkin, A.Y., Silhanek, A.V., Gillijns, W., Moshchalkov, V.V.: Topical review: nucleation of superconductivity and vortex matter in superconductor-ferromagnet hybrids. Supercond. Sci. Technol. 22(5), 053001 (2009)ADSCrossRefGoogle Scholar
  57. 57.
    Ao, P., Thouless, D. J.: Berry’s phase and the magnus force for a vortex line in a superconductor. Phys. Rev. Lett. 70, 2158 (1993)ADSCrossRefGoogle Scholar
  58. 58.
    Other samples have been patterned in which the width of the gap between the contacts is more like a constriction with w∼1μ m or smaller and no revival could be measured, not even a well defined supercurrent. nevertheless some weak non linearity in the I/V characteristics is also present in the shorter channel samples. This seems to prove that space for accomodating vortex dynamics is essential to the mechanism of revival (T. Bauch, private communication).Google Scholar
  59. 59.
    Barone, A., Paternò, G.: Physics and applications of the Josephson effect. Wiley (1982)Google Scholar
  60. 60.
    Martinis, J. M., Kautz, R. L.: Classical phase diffusion in small hysteretic Josephson junctions. Phys. Rev. Lett. 63, 1507–1510 (1989)ADSCrossRefGoogle Scholar
  61. 61.
    Stornaiuolo, D., Rotoli, G., Massarotti, D., Carillo, F., Longobardi, L., Beltram, F., Tafuri, F.: Resolving the effects of frequency-dependent damping and quantum phase diffusion in YBa2Cu3O7−x Josephson junctions. Phys. Rev. B 87, 134517 (2013)ADSCrossRefGoogle Scholar
  62. 62.
    Massarotti, D., Longobardi, L., Galletti, L., Stornaiuolo, D., Montemurro, D., Pepe, G., Rotoli, G., Barone, A., Tafuri, F.: Escape dynamics in moderately damped Josephson junctions (review article). Low Temp. Phys. 38(4), 263–272 (2012)ADSCrossRefGoogle Scholar
  63. 63.
    Svistunov, V. M., D’jachenko, A. I., Tarenkov, V. Y.: Resistive vortices and two-dimensional transition in aluminum films. J. Low Temp. Phys. 57(5), 619–627 (1984)ADSCrossRefGoogle Scholar
  64. 64.
    Ambegaokar, V., Halperin, B. I.: Voltage due to thermal noise in the dc josephson effect. Phys. Rev. Lett. 22, 1364–1366 (1969)ADSCrossRefGoogle Scholar
  65. 65.
    Larkin, A., Varlamov, A.: Theory of Fluctuations in Superconductors. Oxford Scholarship Online (2007)Google Scholar
  66. 66.
    Halperin, B. I., Nelson, D. R.: Resistive transition in superconducting films. J. Low Temp. Phys. 36(5-6), 599 (1979)ADSCrossRefGoogle Scholar
  67. 67.
    Fiory, A. T., Hebard, A. F., Glaberson, W. I.: Superconducting phase transitions in indium/indium-oxide thin-film composites. Phys. Rev. B 28, 5075 (1983)ADSCrossRefGoogle Scholar
  68. 68.
    Mondal, M., Kumar, S., Chand, M., Kamlapure, A., Saraswat, G., Seibold, G., Benfatto, L., Raychaudhuri, P.: Role of the vortex-core energy on the Berezinskii-Kosterlitz-Thouless transition in thin films of NbN. Phys. Rev. Lett. 107, 217003 (2011)ADSCrossRefGoogle Scholar
  69. 69.
    note that our b is defined as in Halperin & Nelson and in Fiory et al, but it is not the one appearing in Mondal et al: \(b_{m} \rightarrow \sqrt {b\:t_{c}}\) Google Scholar
  70. 70.
    Benfatto, L., Castellani, C., Giamarchi, T.: Berezinskii-Kosterlitz-Thouless Transition within the Sine- Gordon Approach: The Role of the Vortex-Core Energy. In: 40 Years of Berezinskii-Kosterlitz-Thouless Theory, pp 161–199. World Scientific, SingaporeGoogle Scholar
  71. 71.
    Yong, J., Lemberger, T. R., Benfatto, L., Ilin, K., Siegel, M.: Robustness of the Berezinskii-Kosterlitz-Thouless transition in ultrathin NbN films near the superconductor-insulator transition. Phys. Rev. B 87, 184505 (2013)ADSCrossRefGoogle Scholar
  72. 72.
    Kessler, B. M., Girit, Ç. Ö., Zettl, A., Bouchiat, V.: Tunable superconducting phase transition in metal-decorated graphene sheets. Phys. Rev. Lett. 104, 047001 (2010)ADSCrossRefGoogle Scholar
  73. 73.
    Allain, A., Han, Z., Bouchiat, V.: Electrical control of the superconducting-to-insulating transition in graphene-metal hybrids. Nat. Mater. 11, 590 (2012)ADSCrossRefGoogle Scholar
  74. 74.
    Giuliano, D., Sodano, P.: Boundary field theory approach to the renormalization of SQUID devices. Nucl. Phys. B 770(3), 332–370 (2007)ADSCrossRefMATHGoogle Scholar
  75. 75.
    Giuliano, D., Sodano, P.: Competing boundary interactions in a Josephson junction network with an impurity. Nucl. Phys. B 837(3), 153–185 (2010)ADSCrossRefMATHGoogle Scholar
  76. 76.
    Cirillo, A., Mancini, M., Giuliano, D., Sodano, P.: Enhanced coherence of a quantum doublet coupled to Tomonaga-Luttinger liquid leads. Nucl. Phys. B 852(1), 235–268 (2011)ADSCrossRefMATHGoogle Scholar
  77. 77.
    Mezzetti, E., Chiodoni, A., Gerbaldo, R., Ghigo, G., Gozzelino, L., Laviano, F., Minetti, B., Amato, A., Rovelli, A., Cherubini, R.: Nanostructured microsize ybco mesas for applications as field sensors. Physica C: Superconductivity and its Applications 468(7–10), 817–819 (2008)ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • D. Massarotti
    • 1
    • 2
  • B. Jouault
    • 3
  • V. Rouco
    • 4
  • G. Campagnano
    • 2
    • 4
  • D. Giuliano
    • 5
    • 6
  • P. Lucignano
    • 2
    • 4
  • D. Stornaiuolo
    • 2
    • 4
  • G. P. Pepe
    • 2
    • 4
  • F. Lombardi
    • 7
  • F. Tafuri
    • 1
    • 2
  • A. Tagliacozzo
    • 2
    • 4
    • 6
  1. 1.Dipartimento di Ingegneria Industriale e dell’InformazioneSeconda Universitá di NapoliAversaItaly
  2. 2.CNR-SPINNapoliItaly
  3. 3.Laboratoire Charles Coulomb UMR 5221Université Montpellier-CNRSMontpellierFrance
  4. 4.Dipartimento di Fisica “E. Pancini”Università di Napoli “Federico II”NapoliItaly
  5. 5.Dipartimento di FisicaUniversità della Calabria Arcavacata di RendeCosenzaItaly
  6. 6.I.N.F.N., Gruppo collegato di CosenzaCosenzaItaly
  7. 7.Department of Microtechnology and NanoscienceChalmers University of TechnologyGöteborgSweden

Personalised recommendations