Fermiology and Superconductivity of Topological Surface States in PdTe₂

The recent discovery of a k_z-dependent series of band inversions has been shown to stabilise a rich array of bulk Dirac fermions and topological surface states in the chalcogen manifolds of transition metal dichalcogenides [1], and has led to speculation that these compounds could hold the necessary prerequisites to host topological superconductivity [2]. Here, we use spin- and angle-resolved photoemission, scanning-tunnelling microscopy and first-principles calculations to investigate PdTe₂, an intrinsic bulk superconductor. We uncover a new set of topological surface states which cross the Fermi level resulting in rich, multi-valley Fermi surfaces possessing an unusual and complex spin-texture. Despite this, our spectroscopy measurements reveal conventional type-II surface superconductivity with no in-gap states. This demonstrates that the presence of Fermi-level pinned topological surface states in an intrinsic superconductor is not a sufficient criterion to realise surface topological superconductivity. [1] Bahramy, Clark et al., Nature Mater. in press (arXiv:1702.08177); [2] Soluyanov. APS Viewpoint, Physics 10, 74.