Superconducting transition temperature near the van Hove singularity: A determinant quantum Monte Carlo study

2D materials are highly tunable systems, naturally providing a fruitful platform to explore various electronic phenomena. When a 2D metal is tuned through a van Hove singularity in the density of states, BCS theory predicts a significant enhancement of the superconducting transition temperature Tc (absent competing instabilities). When the interaction strength increases, however, the picture becomes less clear. We report determinant quantum Monte Carlo results for Tc in the 2D attractive Hubbard model across the van Hove singularity; we observe a negligible enhancement of Tc near the van Hove, even for relatively weak interaction strength. These results suggest that achieving a divergent density of states is not a sufficient criteria for finding high Tc-superconductivity.