Acoustic-phonon-mediated superconductivity in rhombohedral trilayer graphene

TL;DR

This paper explores how acoustic phonons may mediate superconductivity in rhombohedral trilayer graphene, explaining observed phases and predicting critical temperatures near Van Hove singularities.

Contribution

It proposes a phonon-mediated pairing mechanism in rhombohedral trilayer graphene, accounting for two superconducting phases and their distinct origins.

Findings

Superconductivity with $T_c$ up to 3K near Van Hove singularity.

Both $s$-wave spin-singlet and $f$-wave spin-triplet pairings have similar $T_c$.

Superconductivity persists over a wide doping range away from Van Hove singularity.

Abstract

Motivated by the observation of two distinct superconducting phases in the moir\'eless ABC-stacked rhombohedral trilayer graphene, we investigate the electron-acoustic-phonon coupling as a possible pairing mechanism. We predict the existence of superconductivity with the highest $T_c\sim 3$K near the Van Hove singularity. Away from the Van Hove singularity, $T_c$ remains finite in a wide range of doping. In our model, the $s$-wave spin-singlet and $f$-wave spin-triplet pairings yield the same $T_c$, while other pairing states have negligible $T_c$. Our theory provides a simple explanation for the two distinct superconducting phases in the experiment and suggests that superconductivity and other interaction-driven phases (e.g., ferromagnetism) can have different origins.