Extended Data Fig. 7: Photon-energy dependence of the Fermi arc in CoSi.
From: Topological chiral crystals with helicoid-arc quantum states
a, Location of the in-plane momentum direction (black arrow) along which the photon-energy dependence was studied, plotted on the Fermi surface (Fig. 2d) with the surface BZ (red dotted lines). b, MDCs at EF along the in-plane momentum direction illustrated in a, obtained for a series of photon energies from 80 eV to 110 eV in steps of 2 eV. The peak associated with the Fermi arc shows negligible variation in photon energy (dashed line) within the experimental resolution, providing further evidence that the observed Fermi arc is indeed a surface state.
