dHvA Oscillations in High-Tc Compounds

Recent de Haas-van Alphen (dHvA) experiments on high-Tc compounds have been interpreted using Lifshitz-Kosevich (LK) theory, which ignores many-body effects. However in quasi-2d systems, interactions plus Landau level quantization give strong singularities in the self-energy $\Sigma$ and the thermodynamic potential $\Omega$. These are rapidly suppressed as one increases the c-axis tunneling amplitude $t_\perp$ and/or impurity scattering. We show that 2d-3d crossover and interaction effects should show up in these experiments, and that they can lead to strong deviations from LK behaviour. Moreover, dHvA experiments in quasi-2d systems should clearly distinguish between Fermi liquid and non-Fermi liquid states, for sufficiently weak impurity scattering.