Where Is the Electron Located in the Hole-Doped Cuprate?

This chapter illustrates some features in the local density approximation-based electron-structure computational methods, in contrast with the more rigorous variational methods developed for the excitonic complexes. Further, the mixed valence of transition metal ions, Copper included, makes them susceptible to losing electron (hole) again even if once doped with electron (hole). Mobile electrons exist in Copper oxide (CuO₂) planes too, phase-separated from the hole-doped ones. The hole concentration in different p-doped layers varies, which should not come as much of a surprise considering the different distance from the dopant. Similar behaviors exist for electron concentrations in the n-doped layers too. The chapter aims to locate the “alleged” mobile electrons in p-type cuprates. Between 2007 and 2008, the first indications of electron-doping of the CuO₂ layers emerged. Still charge segregation is expected as a general trait of the superconducting cuprates, and this can be interpreted as the so-called heterogeneous charge localization.