ABSTRACT
In this chapter, the authors discuss the band structures of the Tl-based high-Tc superconductors, emphasizing a simple chemical model that is in surprisingly good agreement with the more sophisticated calculations. The Tl-based materials have received much less experimental attention than several other high-temperature superconductors, despite the fact that they have the highest Tcs and other desirable properties for application. There are several reasons why this description is more appropriate in the present context: It makes direct contact with the basic notions of chemical bonding which are so important in the high-Tc materials; it reproduces the results of the more complicated calculations surprisingly well; the model given below is “universal” in that it applies to all the known cuprate and bismuthate high-temperature superconductors; and this model can be easily used by anyone who wants to study the electronic properties of these materials.
