Superconductivity and the periodic table: From elements to materials

Abstract

Based on the normal-state electronic band structure, the necessary condition for a metal to become a superconductor is the simultaneous occurrence of flat and steep bands at the Fermi level. The sufficient condition at least for conventional superconductors is a strong enough coupling of the flat band states to the lattice, e.g. via phonons. Selected elements (Te) and compounds of the rare earth metals (RE2C3, REC2, RE2X2C2 with X = halogen) and MgB2 serve as examples to illustrate the idea.