Enhanced Superconductivity in Quasi Two-Dimensional Systems

We show that the tendency for superconductivity of a weakly coupled 2D electron system can be significantly enhanced if the Fermi energy is close to a logarithmic Van Hove singularity in the density of states. Using results from perturbation theory, supported by quantum Monte Carlo simulations, we calculate $T_c$ and explore the effects of the quasiparticle lifetime and higher-order interactions on this enhancement. This mechanism suggests possible new directions in the search for 2D excitonic superconductivity.