Dirac Dispersions and Fermi Surface Nesting in LaAgSb₂

LaCuSb₂ is a superconductor with a transition temperature of about Tc = 0.9K and is a potential platform where Dirac fermions can be experimentally observed. In this paper, we report systematic high-resolution studies of its electronic structure using the angle-resolved photoemission spectroscopy (ARPES) technique supported by the DFT calculation. The Fermi surface consists of four branches, of which the two inner ones are more 3-dimensional and the theoretical calculations reproduce well the experiment. We observe several linear dispersions forming Dirac-like structures. The nodal lines are present in the system along M-A and X-R and Dirac crossings along X-R are observed by ARPES. Finally, the nesting between external Fermi surface pockets, which corresponds to charge density wave (CDW) modulation vector is enhanced in LaCuSb₂ as compared to LaAgSb₂, while CDW appears in the latter system.