We investigate systematically the bulk and surface electronic structure of the candidate nodal-line semimetal CaAgAs by angle-resolved photoemission spectroscopy and density functional calculations. We observed a metallic, linear, non-$k_z$-dispersive surface band that coincides with the high-binding-energy part of the theoretical topological surface state, proving the topological nontriviality of the system. An overall downshift of the experimental Fermi level points to a rigid-band-like $p$ doping of the samples, due possibly to Ag vacancies in the as-grown crystals.

• Received 21 August 2017

DOI:https://doi.org/10.1103/PhysRevB.96.161112