Electronic structure in high temperature superconducting oxides

The physical properties of High Temperature Superconducting, HTSC, materials have been investigated by the LLNL HTSC program in experiments based on several techniques. Measurements directed at specific determinations of the electronic structure and its relationship to the mechanism of HTSC have been performed using angle resolved photo emission, PE, angular correlation of positron annihilation radiation, ACAR and positron lifetime analysis. Our results provide a partial answer to a question of special significance to the study of high temperature superconductors i.e. the distribution of the electrons in the material, the electronic structure. Special consideration has been given both experimentally and theoretically to the existence and shape of a Fermi surface in the materials. Only one other measurement technique, de Haas van Alphen can provide details of the electronic structure at useful resolutions