Our previous work has demonstrated that Electron Spin Resonance (ESR) is a simple and highly sensitive method to investigate, through changes in the Gd3+ spectra, the magnetic ordering of the CuO2 planes in the parent compounds of the copper oxide superconductors. We propose to extend our research to the doped derivatives that are superconducting. % % % Owing to the strong magnetic correlations in these compounds, it is likely that the microscopic specificity of ESR will be an important contributor to the eventual explanation of high- temperature superconductivity.
