Abstract:
We report on measurements of the dynamic spin susceptibility of the CuO2-planes on single crystals of YBa2Cu3O6+δ using EPR techniques. Intrinsic signals due to the existence of paramagentic chain fragments (pcf) show a behaviour revealing the opening of a spin gap above the superconducting phase-transition temperature. This can be directly compared with the results as observed from neutron scattering and NMR experiments. © 1995.