Electronic band structure of CuBa 2Ca 3Cu 4O 10+ x[formula omitted

Abstract

Electronic band structures of Cu1234O 10 and Cu1234O 11 are calculated by using a full-potential linearized APW method in the local density approximation. Four CuO 2 planes produce four large Fermi surfaces: Two Fermi surfaces are two-dimensional, while the others have a three-dimensional character. The former surfaces are produced by the inner CuO 2 planes of the superconducting layer, and are responsible for the high-temperature superconductivity. The latter surfaces come from the outer CuO 2 planes, and provide the three-dimensional properties in the superconducting state and the normal state. Oxygen doping adds a small amount of holes to only the outer CuO 2 planes, indicating the stable superconducting phase independent of the oxygen content.