Coexistence of Bulk-Nodal and Surface-Nodeless Cooper Pairings in a Superconducting Dirac Semimetal

The interplay of nontrivial topology and superconductivity in condensed matter physics gives rise to exotic phenomena. However, materials are extremely rare where it is possible to explore the full details of the superconducting pairing. Here, we investigate the momentum dependence of the superconducting gap distribution in a novel Dirac material PdTe. Using high resolution, low temperature photoemission spectroscopy, we establish it as a spin-orbit coupled Dirac semimetal with the topological Fermi arc crossing the Fermi level on the (010) surface. This spin-textured surface state exhibits a fully gapped superconducting Cooper pairing structure below Tc similar to 4.5 K. Moreover, we find a node in the bulk near the Brillouin zone boundary, away from the topological Fermi arc. These observations not only demonstrate the band resolved electronic correlation between topological Fermi arc states and the way it induces Cooper pairing in PdTe, but also provide a rare case where surface and bulk states host a coexistence of nodeless and nodal gap structures enforced by spin-orbit coupling.

Automated summary

We investigate the momentum dependence of the superconducting gap distribution in the Dirac material PdTe, and find that it is a spin-orbit coupled Dirac semimetal with a topological Fermi arc. The surface state of PdTe exhibits a fully gapped superconducting Cooper pairing structure below Tc (approximately 4.5 K), while a node is observed in the bulk near the Brillouin zone boundary, away from the topological Fermi arc. These observations demonstrate the band resolved electronic correlation between topological Fermi arc states and their role in Cooper pairing, as well as the coexistence of nodeless and nodal gap structures enforced by spin-orbit coupling in PdTe.