# Dirac point formation revealed by Andreev tunneling in superlattice-graphene/superconductor junctions

## TL;DR

This study demonstrates that Andreev tunneling spectroscopy can effectively detect the formation of new Dirac points in graphene superlattices by revealing distinctive conductance features influenced by the superlattice potential and superconducting correlations.

## Contribution

It introduces a sensitive tunneling spectroscopy method using superconductor-graphene hybrid junctions to identify Dirac point formation in graphene superlattices, highlighting the role of Andreev processes.

## Key findings

- Normalized tunneling conductance shows sharp features at voltages related to Dirac point energy separation.
- Superlattice potential coexists with superconducting correlations, affecting the electronic spectrum.
- Transport properties are significantly altered by the combined effects of superlattice and superconductivity.

## Abstract

A graphene superlattice is formed by a one-dimensional periodic potential and is characterized by the emergence of new Dirac points in the electronic structure. The group velocity of graphene's massless Dirac fermions at the new points is drastically reduced, resulting in a measurable effect in the conductance spectroscopy. We show here that tunnel spectroscopy using a superconducting hybrid junction is more sensitive to the formation of Dirac points in the spectrum of graphene superlattices due to the additional contribution of Andreev processes. We examine the transport properties of a graphene-based superlattice--superconductor hybrid junction and demonstrate that a superlattice potential can coexist with proximity-induced superconducting correlations. Both effects contribute to change graphene's spectrum for subgap energies and, as a result, the normalized tunneling conductance features sharp changes for voltages proportional to the energy separation between the original and the newly generated Dirac points.