DYNAMIC MAGNETIC-SUSCEPTIBILITY OF COPPER-OXIDE SUPERCONDUCTORS IN THE METALLIC STATE

The main features of the spin dynamics within CuO2-layers observed in the YBa2Cu3O6+x system as a function of doping and temperature in the metallic state with magnetic short-range order are well accounted for by a theory based on the t-t'-J model and a slave-fermion approach. Im chi(q, omega) looks like a two-spinon density of states and exhibits a gap at low energy and a cut off at high energy, the uniform suscepti bility vanishes at T = 0. The shape of Im chi(q, omega) as a function of omega is T-dependent.