Spin Dynamics in the Normal State of High T_c Superconductors

We summarize our recent theoretical studies on the spin dynamics in the normal state of the metallic cuprates. The contrasting wave vector dependence of the dynamical spin structure factor $S({\bf q}, \omega )$ in LaSrCuO and YBaCuO systems are attributed to the differences in the fermiology, in conjunction with strong Coulomb correlations. These effects are found to account also for the anomalous temperature and frequency dependence of $S({\bf q}, \omega )$. We conclude that the low energy spin dynamics of the metallic cuprates are described in terms of correlated quasiparticles with a Luttinger Fermi surface and a non-zero antiferromagnetic exchange interaction.
Comment: 30 pages, REVTEX