Breakdown of Fermi Liquid Theory in Doped Mott Insulators by Dynamical Spectral Weight Transfer

TL;DR

This paper demonstrates that doped Mott insulators exhibit a collective degree of freedom due to dynamical spectral weight transfer, leading to the breakdown of Fermi liquid theory, captured by an emergent charge 2e boson mediating new charge e states.

Contribution

It introduces a charge 2e boson emerging from high-energy scale integration in the Hubbard model, explaining the collective behavior and Fermi liquid breakdown in doped Mott insulators.

Findings

Presence of a collective degree of freedom not from elemental excitations.

Emergence of charge 2e boson mediating new charge e states.

Breakdown of Fermi liquid theory in doped Mott insulators.

Abstract

We show that doped Mott insulators exhibit a collective degree of freedom, not made out of the elemental excitations, because the number of single-particle addition states at low energy per electron per spin is greater than one. The presence of such a collective degree of freedom which is not a consequence of proximity to a phase transition is a consequence of dynamical spectral weight transfer from high to low energies. This physics is captured by the charge $2e$ boson that emerges by explicitly integrating out the high-energy scale in the Hubbard model. The charge $2e$ boson binds to a hole, thereby mediating new charge $e$ states at low energy. It is the presence of such charge $e$ states which have no counterpart in the non-interacting system that provides the general mechanism for the breakdown of Fermi liquid theory in doped Mott insulators. The relationship between the charge $2e$ boson formulation and the standard perturbative treatment is explained.