Topological superconductivity in Dirac honeycomb systems

We predict two topological superconducting phases in microscopic models arising from the Berry phase associated with the valley degree of freedom in gapped Dirac honeycomb systems. The first one is a topological helical spin-triplet superconductor with a nonzero center-of-mass momentum that does not break time-reversal symmetry. We also find a topological chiral-triplet superconductor with Chern number +/- 1 with equal-spin pairing in one valley and opposite-spin-triplet pairing in the other valley. Our results are obtained for the Kane-Mele model in which we have explored the effect of three different interactions, onsite attraction U, nearest-neighbor density-density attraction V, and nearest-neighbor antiferromagnetic exchange J, within self-consistent Bogoliubov-de Gennes theory. Transition metal dichalcogenides and cold atom experiments are promising platforms to explore these phases.