Superconductivity from Phonon-Mediated Retardation in a Single-Flavor Metal
Phys. Rev. Lett. 137, 026001 – Published 7 July, 2026
DOI: https://doi.org/10.1103/dcn2-lc8k
Abstract
We study phonon-mediated pairings in a single-flavor metal with a tunable Berry curvature. In the absence of Berry curvature, we discover an unexpected possibility: -wave superconductivity emerging purely from the retardation effect, while the static Bardeen-Cooper-Schrieffer (BCS) approximation fails to predict its existence. The gap function exhibits sign-change behavior in frequency (owing to the dynamical structure of the phonon-mediated interaction in the -wave channel), and obeys a BCS-like scaling. We further show that the Berry curvature stabilizes the chiral -wave superconductivity and can induce transitions to higher-angular-momentum pairings. Our results establish that the phonon-mediated mechanism is a viable pairing candidate in single-flavor systems, such as the quarter-metal superconductivity observed in rhombohedral graphene multilayers.