Truncation of a 2-dimensional Fermi surface due to quasiparticle gap formation at the saddle points

TL;DR

This paper investigates how short-range repulsive interactions in a 2D Fermi liquid cause a Fermi surface truncation due to quasiparticle gap formation at saddle points, revealing similarities to ladder systems.

Contribution

It demonstrates that interactions induce a Fermi surface truncation with gap formation, extending understanding of 2D Fermi liquids and their relation to ladder models.

Findings

Fermi surface truncation occurs at high electron density.

Gap formation at saddle points leads to disconnected Fermi arcs.

Strong coupling fixed point exhibits pairing correlations similar to ladder systems.

Abstract

We study a two-dimensional Fermi liquid with a Fermi surface containing the saddle points $(\pi,0)$ and $(0,\pi)$. Including Cooper and Peierls channel contributions leads to a one-loop renormalization group flow to strong coupling for short range repulsive interactions. In a certain parameter range the characteristics of the fixed point, opening of a spin and charge gap and dominant pairing correlations are similar to those of a 2-leg ladder at half-filling. An increase of the electron density we argue leads to a truncation of the Fermi surface with only 4 disconnected arcs remaining.