Superconducting current and proximity effect in ABA and ABC multilayer graphene Josephson junctions

TL;DR

This study uses numerical methods to analyze how stacking order in multilayer graphene affects the proximity effect and supercurrent flow in Josephson junctions, revealing stacking-dependent differences in current distribution and pair amplitude polarization.

Contribution

It provides a detailed numerical analysis of the impact of ABA and ABC stacking on superconducting proximity effects and supercurrent behavior in multilayer graphene Josephson junctions.

Findings

Stacking order significantly influences supercurrent distribution.

Rhombohedral stacking enhances pair amplitude polarization.

Supercurrent is suppressed despite increased proximity effect in non-dimer sites.

Abstract

Using a numerical tight-binding approach based on the Chebyshev-Bogoliubov-de Gennes method we describe Josephson junctions made of multilayer graphene contacted by top superconducting gates. Both Bernal (ABA) and rhombohedral (ABC) stacking are considered and we find that the type of stacking has a strong effect on the proximity effect and the supercurrent flow. For both cases the pair amplitude shows a polarization between dimer and non-dimer atoms, being more pronounced for rhombohedral stacking. Even though the proximity effect in non-dimer sites is enhanced when compared to single layer graphene, we find that the supercurrent is suppressed. The spatial distribution of the supercurrent shows that for Bernal stacking the current flows only in the top-most layers while for rhombohedral stacking the current flows throughout the whole structure.