Chiral d-wave superconductivity in SrPtAs: A Weyl superconductor

Recent $\mu$SR measurements suggest that the hexagonal pnictide SrPtAs is a chiral d-wave superconductor that spontaneously breaks time-reversal symmetry in the superconducting state. The $d$-wave order parameter fully gaps all Fermi surfaces, except for point nodes on one Fermi surface sheet near the $K$ and $K'$ points at the Brillouin zone corners. Theses nodal points are Majorana-Weyl fermions in momentum space. We study the topological characteristics of this superconducting phase, which features protected chiral surface states, Majorana-Fermi arcs on the surface and an associated thermal Hall response.