Marginal Fermi Liquid Theory in the Hubbard Model

TL;DR

This paper demonstrates Marginal Fermi Liquid behavior in the Hubbard model using a self-consistent projection operator method, revealing doping-dependent Fermi surface changes and a transition to Fermi liquid behavior.

Contribution

It introduces a high-resolution, self-consistent approach to study single-particle excitations in the Hubbard model, highlighting doping-induced phase transitions and deviations from Luttinger's theorem.

Findings

MFL behavior observed in the Hubbard model for various doping levels

Fermi surface changes from hole-like to electron-like with doping

Discontinuous transition from MFL to Fermi liquid at certain doping levels

Abstract

We find Marginal Fermi Liquid (MFL) like behavior in the Hubbard model on a square lattice for a range of hole doping and on-site interaction parameter U. Thereby we use a self-consistent projection operator method. It enables us to compute the momentum and frequency dependence of the single-particle excitations with high resolution. The Fermi surface is found to be hole-like in the underdoped and electron-like in the overdoped regime. When a comparison is possible we find consistency with finite temperature quantum Monte Carlo results. We also find a discontinuous change with doping concentration from a MFL to Fermi liquid behavior resulting from a collapse of the lower Hubbard band. This renders Luttinger's theorem inapplicable in the underdoped regime.