Dirac-Like Electronic-Band Dispersion Of Lasb2 Superconductor And Its Counterpart Laagsb2

Electronic properties of the LaSb2 superconductor and its non-superconducting LaAgSb2 analogue are determined within the density functional theory approach. The existence of 2D Dirac fermions in the bulk electronic structure of both compounds is unveiled and analysed based on weighted bands calculated around the Fermi level. Interestingly, a lack of superconductivity in LaAgSb2 can be explained in terms of the topological Feshbach shape resonance of some Fermi surface sheets, associated with the reduction of their dimensionality (from 3D to 2D).