Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Transport: Poster Session

TT 29.8: Poster

Donnerstag, 8. September 2022, 15:00–18:00, P1

Andreev reflection in gated bilayer graphene — •Panch Ram¹, Detlef Beckmann², Romain Danneau², and Wolfgang Belzig¹ — ¹Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany — ²Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany

In this poster, we will present our recent theoretical study of the NS junction Andreev reflection and differential conductance on the bilayer graphene including different (equal and opposite) onsite potential for each monolayer graphene. We employ the Dirac-Bogoliubov de Gennes (DBdG) equation for the low-energy bilayer graphene Hamiltonian and calculate the Andreev reflection (retroreflection as well as specular) and differential conductance (within the Blonder-Tinkham-Klapwijk formalism [1-2]) for the junction in two different parameters limits: (i) interlayer coupling is larger energy scale (ii) superconducting-side doping potential is larger energy scale [3-5]. We obtain the Andreev retro-reflection (specular reflection) below (above) the normal-side Fermi energy when the bias voltage is less than the superconducting gap. We also observe that both retro and specular Andreev reflections are strongly modified by the gate field.

[1] A. F. Andreev, Sov. Phys. JETP 19, 1228 (1964)

[2] G. E. Blonder et. al, Phys. Rev. B 25, 4515 (1984)

[3] C. W. J. Beenakker, Phys. Rev. Lett. 97, 067007 (2006)

[4] T. Ludwig, Phys. Rev. B 75, 195322 (2007)

[5] D. K. Efetov and K. B. Efetov, Phys. Rev. B 94, 075403 (2016)