Chiral triplet superconductivity on the graphene lattice

J. P. L. Faye; P. Sahebsara; D. Sénéchal

doi:10.1103/PhysRevB.92.085121

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Chiral triplet superconductivity on the graphene lattice

J. P. L. Faye, P. Sahebsara, D. Sénéchal

DOI 10.1103/PhysRevB.92.085121 · Physical Review B

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Abstract

Motivated by the possibility of superconductivity in doped graphene sheets, we investigate superconducting order in the extended Hubbard model on the two-dimensional graphene lattice using the variational cluster approximation (VCA) and the cellular dynamical mean-field theory (CDMFT) with an exact diagonalization solver at zero temperature. The nearest-neighbor interaction is treated using a mean-field decoupling between clusters. We compare different pairing symmetries, singlet and triplet, based on short-range pairing. VCA simulations show that the real (nonchiral), triplet p-wave symmetry is favored for small V, small onsite interaction U, or large doping, whereas the chiral combination p+ip is favored for larger values of V, stronger onsite interaction U, or smaller doping. CDMFT simulations confirm the stability of the p+ip solution, even at half-filling. Singlet superconductivity (extended s wave or d wave) is either absent or subdominant.