Topological p+IP superconductivity in doped graphene-like single-sheet materials BC3

We theoretically study exotic superconducting phases in graphene-like single-sheet material BC3 doped to its type-II van Hove singularity whose saddle-point momenta are not time-reversal invariant. From combined renormalization group analysis and random-phase approximation calculations, we show that the dominant superconducting instability induced by weak repulsive interactions is in the time-reversal-invariant p+IP pairing channel because of the interplay among dominant ferromagnetic fluctuations, subleading spin fluctuations at finite momentum, and spin-orbit coupling. Such time-reversal-invariant p+IP superconductivity has nontrivial Z2 topological invariant. Our results show that doped BC3 provides a promising route to realizing a genuine two-dimensional helical p+IP superconductor.