Fractionalized Fermi Liquid in a Kondo-Heisenberg Model

TL;DR

This paper demonstrates the existence of a fractionalized Fermi liquid state in the Kondo-Heisenberg model, characterized by unbroken translational symmetry and a Fermi surface not determined by electron density, using a non-perturbative exact approach.

Contribution

It provides a microscopic, non-perturbative demonstration of a fractionalized Fermi liquid state in a Kondo-Heisenberg model, confirming theoretical predictions.

Findings

Existence of a fractionalized Fermi liquid state with unbroken translational symmetry.

Coexistence of well-defined quasiparticles and gapped fractionalized excitations.

Phase transition to ordered states like charge density wave or superconductivity at low temperature.

Abstract

The Kondo-Heisenberg model is used for a microscopic demonstration of existence of a peculiar metallic state with unbroken translational symmetry where the Fermi surface volume is not controlled by the total electron density. I use a non-perturbative approach where the strongest interactions are taken into account by means of exact solution, and corrections are controllable. In agreement with the general requirements formulated in (T. Senthil {\it et.al.} Phys. Rev. Lett. {\bf 90}, 216403 (2003)), the resulting metallic state represents a fractionalized Fermi liquid where well defined quasiparticles coexist with gapped fractionalized collective excitations. The system undergoes a phase transition to an ordered phase (charge density wave or superconducting), at the transition temperature which is parametrically small in comparison to the quasiparticle Fermi energy.