Fermi Liquid Properties of a Two Dimensional Electron System With the Fermi Level Near a van Hove Singularity

TL;DR

This paper investigates the low energy properties of a two-dimensional electron system near van Hove singularities, finding that it generally behaves as a normal Fermi liquid with well-defined quasiparticles, relevant to high-temperature superconductivity.

Contribution

It provides a diagrammatic analysis showing that such systems predominantly exhibit Fermi liquid behavior despite the van Hove singularities.

Findings

System behaves as a normal Fermi liquid in most regions of the phase diagram.

Imaginary part of self-energy is much smaller than excitation energy.

Single particle properties are weakly affected by van Hove singularities.

Abstract

We use a diagrammatic approach to study low energy physics of a two dimensional electron system where the Fermi level is near van-Hove singularies in the energy spectrum. We find that in most regions of the $\epsilon_F-T$ phase diagram the system behaves as a normal Fermi liquid rather than a marginal Fermi liquid. Particularly, the imaginary part of the self energy is much smaller than the excitation energy, which implies well defined quasiparticle excitations, and single particle properties are only weakly affected by the presence of the van-Hove singularities. The relevance to high temperature superconductivity is also discussed.