Superconductivity from Repulsive Interactions in Rhombohedral Trilayer Graphene: a Kohn-Luttinger-Like Mechanism

TL;DR

This paper demonstrates that rhombohedral trilayer graphene can exhibit spin-triplet superconductivity driven solely by long-range Coulomb repulsion, with critical temperatures up to 0.15 K, differing from other graphene systems.

Contribution

It reveals a novel repulsive-interaction-driven superconducting phase in rhombohedral trilayer graphene, distinct from twisted graphene layers, emphasizing a Kohn-Luttinger-like mechanism.

Findings

Superconductivity in rhombohedral trilayer graphene driven by Coulomb repulsion.

Spin-triplet pairing with critical temperatures up to 0.15 K.

Order parameter modulation within Fermi surface pockets.

Abstract

We study the emergence of superconductivity in rhombohedral trilayer graphene due purely to the long-range Coulomb repulsion. This repulsive-interaction-driven phase in rhombohedral trilayer graphene is significantly different from those found in twisted bilayer and trilayer graphenes. In the latter case, the nontrivial momentum-space geometry of the Bloch wavefunctions leads to an effective attractive electron-electron interaction; this allows for less modulated order parameters and for spin-singlet pairing. In rhombohedral trilayer graphene, we instead find spin-triplet superconductivity with critical temperatures up to 0.15 K. The critical temperatures strongly depend on electron filling and peak where the density of states diverge. The order parameter shows a significant modulation within each valley pocket of the Fermi surface.