Authors
Abstract
We study tunneling conductance of a graphene based normal metal-insulator-superconductor (NIS) junction with Corbino disk structure. Solving Dirac-Bogolioubov- De Gennes (DBdG) equation in different regions of the junction and employing scattering approach we obtain normal and Andreev reflection coefficients of the junction. Using Blonder-Tinkham-Klapwijk (BTK) formula we calculate tunneling conductance of the junction as a function of the barrier strength of insulating region. The obtained results show that tunneling conductance of the junction oscillates as a function of the barrier strength as in the planar structure case. The tunneling conductance shows maximums at resonances which have a pi/2 phase shift with respect to the planar structure.
Keywords
2. K.S. Novoselov et al., “Two-dimensional gas of massless Dirac fermions in grapheme”; Nature 438, 197 (2005).
3. C.W.J. Beenakker, “Specular Andreev reflection in graphene” Phys. Rev. Lett 97, 067007 (2006).
4. .M. Titov and C.W.J. Beenakker, “Josephson effect in ballistic graphene” Phys. Rev. B 74, 041401(R) (2006).
5. Ali G. Moghaddam, M. Zareyan, “Josephson effect in mesoscopic graphene strips with finite width” Phys. Rev. B 74, 241403(R) (2006).
6. Ali. G. Moghaddam and M. Zareyan “Graphene based superconducting quantum point contacts”
Appl. Phys. A 89, 579-585 (2007).
7. J. Gonzalez, and E. Perfetto, “Critical currents in graphene Josephson junctions” J. Phys.: Condens. Matter 20, (2008).
8. Xu Du, Ivan Skachko, and Eva Y. Andrei, “Josephson current and multiple andreev reflections in graphene sns junctions” Phys. Rev. B 77, 184507 (2008).
9. F. Miao, S. Wijeratne, Y. Zhang, et al., “Phase-Coherent Transport in Graphene Quantum Billiards” Science 317, 1530 (2007).
10. Subhro Bhattacharjee and K.Sengupta, “Tunneling conductance of graphene nis junctions” Phys. Rev. Lett 97, 217001 (2006).
11. Babak Abdollahipour and Elham Moomivand “Magnetopumping current in graphene Corbino pump” Physica E 86, 204–209 (2017).
12. P. Recher, B. Trauzettel, A. Rycerz, M. Blanter, C.W.J. Beenakker and A.F. Morpurgo, “Aharonov-Bohm effect and broken valley degeneracy in graphene rings” Phys. Rev. B 76, 235404 (2007).
13. G.E. Blonder, M. Tinkham, and T. M. Klapwijk, “Transition from metallic to tunneling regimes in superconducting microconstrictions: Excess current, charge imbalance, and supercurrent conversion” Phys. Rev. B 25, 4515 (1982).
)