Excitonic Tunneling in the AB-bilayer Graphene Josephson Junctions

TL;DR

This paper investigates excitonic tunneling phenomena in AB-stacked bilayer graphene Josephson junctions, highlighting the effects of Coulomb interactions, excitonic pairing, and phase coherence on tunneling currents.

Contribution

It provides a comprehensive calculation of normal and excitonic tunnel currents using exact four-band dispersions without low-energy approximations, considering Coulomb interactions and excitonic effects.

Findings

Degeneracy of ground state at zero voltage

Presence of dc Josephson current due to excitonic condensates

Variation of tunneling currents with gate voltage and interaction parameters

Abstract

We have considered the AB-stacked bilayer graphene Josephson junction. The bilayers are supposed to be in the charge equilibrium states and at the half-filling in each of the electronic layers of the construction and at each value of the external gate. By considering the interacting bilayers in both sides of the junction and by taking into account both intralayer and interlayer Coulomb interaction effects, we have calculated the normal and excitonic tunnel currents through the junction. The electronic band renormalizations have been taken into account, due to the excitonic pairing effects and condensation in the BLGs. The exact four-band energy dispersions, including the excitonic renormalizations, have been used for the bilayers without any low-energy approximation. We show the degeneracy of the ground state at the zero applied voltage and for different phases of the coherent condensates by showing a dc Josephson current through the junction. The normal and excitonic tunneling currents have been calculated for different gate voltages and for different values of the interaction parameters. The role of the charge neutrality point has been discussed in details.