Correlation-induced triplet superconductivity on the graphene lattice

TL;DR

This paper explores how electron correlations on the graphene lattice can induce triplet superconductivity, revealing multiple near-degenerate solutions with different symmetries, including p-wave and f-wave types.

Contribution

It demonstrates that within the Hubbard model, triplet superconductivity is favored over singlet, introducing multiple symmetry solutions and a novel p+ip state breaking time-reversal symmetry.

Findings

Triplet superconductivity is favored over singlet on the graphene lattice.

Multiple solutions with different symmetries are nearly degenerate.

A p+ip solution that breaks time-reversal symmetry is identified.

Abstract

We investigate the possibility of superconductivity on the graphene lattice within the repulsive Hubbard model using the variational cluster approximation (VCA). We find that singlet superconductivity is impossible; instead, triplet superconductivity is favored, with four solutions that are close to each other in energy and differ by their symmetry; one is f-wave, the other three p-wave, including a p+ip solution that breaks time-reversal invariance.