Fig. 4. Density of states (DOS) of the effective low-energy model.
a DOS for the surface bands of RhBi2 in the vicinity of the point as a function of energy (E = 0 is the location of the Fermi energy). The DOS exhibits a logarithmic divergence at E = − 85 meV (due to saddle points) and vanishes at E = − 83 meV (due to nodal Dirac point), and is nearly constant for energies E < − 85 meV. b Enhancement of superconducting transition temperature Tc/Tc,0 at the van Hove singularity as a function of the bare dimensionless superconducting coupling λ = gρ0/2 in the weak-coupling regime. Here, Tc,0 is the superconducting transition temperature for chemical potential away from van Hove point, while Tc is the transition temperature for EF tuned to van Hove singularity. Note that Tc is normalized by D, while Tc,0 is normalized by the cutoff Λ.