This is a joint effort (involving LSU, UT and ORNL) to study intrinsic, normal-state electronic properties of materials that form high-temperature superconductors. Measurements will be made of Landau quantum oscillations in both the normal (n) and superconducting (sc) mixed states . The physics studied includes Fermi-surface topologies, effective masses and scattering rates for electrons in the n state; the interaction of n electrons with flux vortices in the mixed state; and superconductivity in the presence of a strongly Landau-quantized, n-state background. % % % The measurements are expected to furnish unique data that will lead to a better understanding of the precise nature of high- temperature superconductivity.