Superconductivity in type II layered Weyl semi-metals

Novel ‘quasi 2D’ typically layered (semi)metals offer a unique opportunity to control the density and even the topology of electronic matter. In intercalated MoTe ₂ type II Weyl semi-metal the tilt of the dispersion relation cones is so large that topologically the Fermi surface is distinct from a more conventional type I. Superconductivity observed recently in this compound (Zhang et al 2022 2D Mater. 9 045027) demonstrated two puzzling phenomena. The gate voltage has no impact on critical temperature, T c , in a wide range of density, while it is very sensitive to the inter-layer distance. A phonon theory of pairing in a layered Weyl material including the effects of Coulomb repulsion is constructed, which explains the above two features in MoTe ₂. The first feature turns out to be a general one for any type II topological material, while the second reflects properties of the intercalated materials affecting the Coulomb screening.