Superconductivity from electronic interactions and spin-orbit enhancement in bilayer and trilayer graphene

TL;DR

This paper proposes a mechanism for superconductivity in bilayer and trilayer graphene driven by electronic interactions, with spin-orbit coupling enhancing the critical temperature and influencing the order parameter's properties.

Contribution

It demonstrates that Coulomb interactions can induce superconductivity in graphene layers and shows how spin-orbit coupling enhances critical temperatures and affects the order parameter.

Findings

Superconductivity arises from Coulomb interactions in graphene layers.

Spin-orbit coupling significantly increases the critical temperature.

The superconducting state is valley-singlet and spin-triplet.

Abstract

We discuss a Kohn-Luttinger-like mechanism for superconductivity in Bernal bilayer graphene and rhombohedral trilayer graphene. Working within the continuum model description, we find that the screened long-range Coulomb interaction alone gives rise to superconductivity with critical temperatures that agree with experiments. We observe that the order parameter changes sign between valleys, which implies that both materials are valley-singlet, spin-triplet superconductors. Adding Ising spin-orbit coupling leads to a significant enhancement in the critical temperature, also in line with experiment, and the superconducting order parameter shows locking between the spin and valley degrees of freedom.