Extended Data Fig. 7: Constant-energy contours and calculated electronic susceptibility plots.
From: Tunable topologically driven Fermi arc van Hove singularities
a, b, Surface-sensitive ARPES measured constant-energy contours of the surface helicoid arcs in CoSi. The solid blue line represents a fit that tracks the trajectory of the helicoid arcs at E = 0 meV (panel a) and E = − 0.01 eV (panel b). The red box indicates the (001) surface Brillouin zone. c, d, Electronic susceptibility χq plot calculated using the ARPES measured constant energy contours at E = 0 eV (panel c) and E = − 0.01 eV (panel d). Up to symmetry-equivalent scattering vectors, the strong peaks represent all the different peaks in the scattering BZ, which are labeled as Q. The Q vectors, nearest and next- nearest to the \(\bar{{{\Gamma }}}\)-point are labeled Q1 and Q2, respectively. The Q1-vector is annotated by the green arrow, potentially connected to the nesting vectors inside the intra-helicoid arc van Hove singularity. The Q2-vector is annotated by the cyan arrow, potentially connected to nesting vectors linking the nearest inter-helicoid arc van Hove singularity. The length and direction of arrows with the same color remains equivalent when comparing panels (a), (b) to panels (c), (d).
