Tunneling Conductance in Strained Graphene-Based Superconductor: Effect of Asymmetric Weyl–Dirac Fermions

Original Paper

Abstract

Based on the BTK theory, we investigate the tunneling conductance in uniaxially strained graphene-based normal metal (NG)/barrier (I)/superconductor (SG) junctions. In the present model, we assume that by depositing the conventional superconductor on the top of the uniaxially strained graphene, normal graphene may turn to superconducting graphene with the Cooper pairs formed by the asymmetric Weyl–Dirac electrons, the massless fermions with direction-dependent velocity. The highly asymmetrical velocity, vy/vx≫1, may be created by strain in the zigzag direction near the transition point between gapless and gapped graphene. In the case of highly asymmetrical velocity, we find that the Andreev reflection strongly depends on the direction of strain, and the current perpendicular to the direction of strain can flow through the junction as if there were no barrier. Also, the current parallel to the direction of strain anomalously oscillates as a function of the gate voltage with very high frequency. Our predicted result is quite different from the feature of the quasiparticle tunneling in the unstrained graphene-based NG/I/SG conventional junction. This is because of the presence of the direction-dependent-velocity quasiparticles in the highly strained graphene system.

Keywords

Tunneling conductance Strained graphene Specular Andreev reflection N/I/S junction 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Novoselov, K.S., et al.: Science 306, 666 (2004) ADSCrossRefGoogle Scholar
  2. 2.
    Novoselov, K.S., et al.: Nature 438, 197 (2005) ADSCrossRefGoogle Scholar
  3. 3.
    Zhang, Y., et al.: Nature 438, 201 (2005) ADSCrossRefGoogle Scholar
  4. 4.
    Wallace, P.R.: Phys. Rev. 71, 622 (1947) ADSMATHCrossRefGoogle Scholar
  5. 5.
    Klein, O.: Z. Phys. 53, 157 (1929) ADSCrossRefGoogle Scholar
  6. 6.
    Heersche, H.B., et al.: Nature 446, 56 (2007) ADSCrossRefGoogle Scholar
  7. 7.
    Aristizabal, C.O., et al.: Phys. Rev. B 79, 165436 (2009) ADSCrossRefGoogle Scholar
  8. 8.
    Beenakker, C.W.J.: Phys. Rev. Lett. 97, 067007 (2006) ADSCrossRefGoogle Scholar
  9. 9.
    Andreev, A.F.: Sov. Phys. JETP 19, 1228 (1964) Google Scholar
  10. 10.
    Blonder, G.E., et al.: Phys. Rev. B 25, 4515 (1982) ADSCrossRefGoogle Scholar
  11. 11.
    Bhattacharjee, S., Sengupta, K.: Phys. Rev. Lett. 97, 217001 (2006) ADSCrossRefGoogle Scholar
  12. 12.
    Lender, J., Sudbo, A.: Phys. Rev. B 77, 064507 (2008) ADSCrossRefGoogle Scholar
  13. 13.
    Soodchomshom, B., et al.: Physica C 469, 689 (2009) ADSCrossRefGoogle Scholar
  14. 14.
    Zhai, F., et al.: Phys. Rev. B 82, 115442 (2010) ADSCrossRefGoogle Scholar
  15. 15.
    Lu, Y., Guo, J.: Appl. Phys. Lett. 97, 073105 (2010) ADSCrossRefGoogle Scholar
  16. 16.
    Pereira, V.M., Neto, A.H.C.: Phys. Rev. Lett. 103, 046801 (2009) ADSCrossRefGoogle Scholar
  17. 17.
    Low, T., Guinea, F.: Nano Lett. 10, 3551 (2010) ADSCrossRefGoogle Scholar
  18. 18.
    Levy, N., et al.: Science 329, 544 (2010) ADSCrossRefGoogle Scholar
  19. 19.
    Kang, J., et al.: Appl. Phys. Lett. 96, 252105 (2010) ADSCrossRefGoogle Scholar
  20. 20.
    Ni, Z.H., et al.: ACS Nano 2, 2301 (2008) CrossRefGoogle Scholar
  21. 21.
    Pereira, V.M., et al.: Phys. Rev. B 80, 045401 (2009) ADSCrossRefGoogle Scholar
  22. 22.
    Choi, S.-M., et al.: Phys. Rev. B 81, 081407 (R) (2010) ADSGoogle Scholar
  23. 23.
    Treidel, O.-B., et al.: Phys. Rev. Lett. 104, 063901 (2010) ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Thailand Center of Excellence in Physics, Commission Higher on EducationMinistry of EducationBangkokThailand

Personalised recommendations