Electronic structure of TlBaCaCuO high T_c superconductors

We discuss the variation of total and projected electronic densities of states at the Fermi level in the TlBa2CaL-1Cu3O2L+3 series for L = 1 to 5. Simple BCS-type theories relating Tc to N(EF) suggest that only the broad CuO bands contribute to superconductivity, since the inclusion of narrow TlO band contributions to N(EF) leads to an irregular variation of N(EF) with the number of CuO2 layers. Other important band structure features are also considered. © 1989.