SPIN DYNAMICS AND IMPLICATIONS FOR SUPERCONDUCTIVITY - SOME PROBLEMS WITH THE D-WAVE SCENARIO

We review the spin dynamics of the normal state of the cuprates with special emphasis on neutron data in both the YBa2Cu3O7-delta and La2-xSrCuO4 systems. When realistic models of the Fermi surface shapes are incorporated, along with a moderate degree of spin fluctuations, we find good semiquantitative agreement with experiment for both cuprates. Building on the success of this Fermi-liquid-based scheme, we explore the implications for d-wave pairing from a number of vantage points. We conclude that our present experimental and theoretical understanding is inadequate to confirm or refute the d-wave scenario.