Realistic mechanisms for removing Na3Bi double surface Fermi arcs

Determine whether bulk perturbations that preserve all bulk symmetries or sufficiently strong surface potentials can remove double surface Fermi arcs in realistic Na3Bi systems, rather than only in simplified theoretical models.

Background

Double surface Fermi arcs in Na3Bi are not protected in the same robust manner as Weyl-semimetal Fermi arcs. Prior four-band tight-binding studies suggested that symmetry-preserving bulk perturbations can eliminate them, while low-energy effective models indicated that sufficiently strong surface potentials can also remove them. The unresolved issue is whether either mechanism corresponds to physically realistic modifications of pristine Na3Bi. The paper addresses this question by constructing realistic DFT-derived tight-binding models for thick Na3Bi (100) slabs and examining two explicit surface terminations.