Energy structure and g-factors of Cu2+ ion in high temperature superconductors

Energy structure and g-facrtors of Cu2+ ion in the field of the nearest oxygen ligands center different types of coordination by ligands are calculated. Comparison of calculation results with experimental data on Cu2+ ESR in a series of metal oxides indicates that Cu2+ ions, existing in an inordinary (deficient) oxygen environment are responsible for ESR signal in high-temperature superconductors (HTSC). The proposed concept of magnetic moment localization on copper ions in the deficient environment allows one to percive the nature of active ESR-centers in HTSC and the observed correlation between HTSC parameters and Cu2+ ESR signal intensity in them