Electronic Structure and Kohn-Luttinger Superconductivity of Heavily-Doped Single-Layer Graphene

TL;DR

This paper predicts the possibility of topological d+id superconductivity in heavily-doped single-layer graphene, with a critical temperature up to 600 mK, using a Kohn-Luttinger mechanism and considering various dopants.

Contribution

It introduces a theoretical framework predicting topological superconductivity in doped graphene, highlighting the effects of different dopants on superconducting states.

Findings

Robust d+id topological SC predicted in Tb-doped graphene.

Critical temperature up to 600 mK for the SC.

Dopants altering lattice symmetry suppress d-wave SC.

Abstract

The existence of superconductivity (SC) in graphene appears to be established in both twisted and non-twisted multilayers. However, whether their building block, single-layer graphene (SLG), can also host SC remains an open question. Earlier theoretical works predicted that SLG could become a chiral d-wave superconductor driven by electronic interactions when doped to its van Hove singularity, but questions such as whether the d-wave SC survives the strong band renormalizations seen in experiments, its robustness against the source of doping, or if it will occur at any reasonable critical temperature (Tc) have remained difficult to answer, in part due to uncertainties in model parameters. In this study, we adopt a random-phase approximation framework based on a Kohn-Luttinger-like mechanism to investigate SC in heavily-doped SLG. We predict that robust d+id topological SC could arise in SLG doped by Tb, with a Tc up to 600 mK. We also investigate the possibility of realizing d-wave SC by employing other dopants, such as Li or Cs. The structural models have been derived from angle-resolved photoemission spectroscopy measurements on Tb-doped graphene and first-principles calculations for Cs and Li doping. We find that dopants that change the lattice symmetry of SLG are detrimental to the d-wave state. The stability of the d-wave SC predicted here in Tb-doped SLG could provide a valuable insight for guiding future experimental efforts aimed at exploring topological superconductivity in monolayer graphene.