Soft Fermi Surfaces and Breakdown of Fermi Liquid Behavior

TL;DR

This paper investigates how electron interactions near a d-wave Pomeranchuk instability in two dimensions cause anisotropic decay of quasiparticles, leading to the breakdown of Fermi liquid behavior except along certain directions.

Contribution

It demonstrates that critical Fermi surface fluctuations induce anisotropic quasiparticle decay, fundamentally altering Fermi liquid theory near a Pomeranchuk instability.

Findings

Fermi liquid behavior is destroyed over most of the Fermi surface.

Anisotropic decay rates are significantly enhanced near the instability.

Fermi surface deformations break lattice symmetry and induce collective fluctuations.

Abstract

Electron-electron interactions can induce Fermi surface deformations which break the point-group symmetry of the lattice structure of the system. In the vicinity of such a "Pomeranchuk instability" the Fermi surface is easily deformed by anisotropic perturbations, and exhibits enhanced collective fluctuations. We show that critical Fermi surface fluctuations near a d-wave Pomeranchuk instability in two dimensions lead to large anisotropic decay rates for single-particle excitations, which destroy Fermi liquid behavior over the whole surface except at the Brillouin zone diagonal.