Pseudogapped Fermi liquids from emergent quasiparticles

TL;DR

This paper introduces an exactly solvable interacting fermionic model that exhibits a pseudogapped Fermi liquid state with emergent quasiparticles, providing insights into non-Mott pseudogap phenomena and phase transitions.

Contribution

It presents a novel exactly solvable model producing a pseudogapped Fermi liquid without Mott physics, using a fermionic mechanism and path-integral techniques.

Findings

Demonstrates temperature-dependent pseudogap opening.

Shows violation of Luttinger sum rule.

Analyzes quantum phase transitions between pseudogapped and Landau Fermi liquids.

Abstract

We propose an interacting model that is exactly solvable in any spatial dimension and gives rise to a Fermi liquid (FL) featuring a pseudogapped (PG) single-particle spectral function and a vanishing quasiparticle (QP) weight at half-filling, without invoking Mott physics. The PG originates from a purely fermionic mechanism through emergent QPs arising from a correlated hopping interaction. By employing an appropriate coherent-state basis, we derive a Gaussian path-integral representation of the partition function, which enables systematic treatments of deviations from the Gaussian limit using standard many-body techniques, such as diagrammatic perturbation theory or mean-field theory. We explicitly demonstrate and discuss several properties of the exactly solvable limit on the square lattice, including the mechanism for temperature-dependent PG opening, the singular behavior of the self-energy, the violation of the Luttinger sum rule, and the role of Luttinger and Fermi surfaces. Finally, we explore quantum phase transitions between PG-FLs and Landau FLs.