The development of the method for low-temperature investigations of HTSC systems on the X-ray electron magnetic spectrometer

An X-ray electron magnetic spectrometer equipped with an adapter for studying samples at low-temperatures was used for the detailed investigation of the peculiarities of the chemical structure of bulk polycrystalline HTSC samples Bi2Sr2CaCu2O8, BiSrCaCu2O5.5, BiSrCaCu3O8 and YBau3O7-δ at room temperature and the superconductivity temperature. The investigations show that at the superconductivity temperature, the covalent bond between copper and oxygen atoms is formed owing to the Cu2+ copper ions. In the superconducting state, when the hybridization of the copper and oxygen electrons d(Cu)-p(O) increases, the d-electron density near EF is growing. After the system transition in the superconducting state, the appearance of the additional maxima in the O1s- and Sr3d-spectra (Ba3d) indicates the changes in the nearest environment of the O and Sr (Ba) atoms, specifically, the appearance of the strontium atoms with a greater degree of oxidation