How to induce superconductivity in epitaxial graphene $via$ remote proximity effect through an intercalated gold layer

TL;DR

This paper demonstrates a method to induce superconductivity in epitaxial graphene via a remote proximity effect through an intercalated gold layer, preserving graphene's electronic properties while overcoming substrate limitations.

Contribution

The study introduces a novel intercalation strategy using gold to induce superconductivity in epitaxial graphene without destroying its Dirac electronic structure.

Findings

Superconductivity successfully induced in graphene via gold intercalation.

Reduced graphene corrugation indicates weak graphene-Au interaction.

High density of point defects in graphene due to intercalation.

Abstract

Graphene holds promises for exploring exotic superconductivity with Dirac-like fermions. Making graphene a superconductor at large scales is however a long-lasting challenge. A possible solution relies on epitaxially-grown graphene, using a superconducting substrate. Such substrates are scarce, and usually destroy the Dirac character of the electronic band structure. Using electron diffraction (reflection high-energy, and low-energy), scanning tunneling microscopy and spectroscopy, atomic force microscopy, angle-resolved photoemission spectroscopy, Raman spectroscopy, and density functional theory calculations, we introduce a strategy to induce superconductivity in epitaxial graphene $via$ a remote proximity effect, from the rhenium substrate through an intercalated gold layer. Weak graphene-Au interaction, contrasting with the strong undesired graphene-Re interaction, is demonstrated by a reduced graphene corrugation, an increased distance between graphene and the underlying metal, a linear electronic dispersion and a characteristic vibrational signature, both latter features revealing also a slight $p$ doping of graphene. We also reveal that the main shortcoming of the intercalation approach to proximity superconductivity is the creation of a high density of point defects in graphene (10$^{14}$~cm$^{-2}$). Finally, we demonstrate remote proximity superconductivity in graphene/Au/Re(0001), at low temperature.