A large-N analysis of the local quantum critical point and the spin-liquid phase

TL;DR

This paper analytically investigates a Kondo lattice model with antiferromagnetic interactions, revealing a local quantum critical point and a spin-liquid phase with diverging spin susceptibility, supported by quantum Monte Carlo simulations.

Contribution

It introduces a large-N analytical framework to study the quantum critical point and spin-liquid phase in the Kondo lattice model, with validation from numerical simulations.

Findings

Identification of a local quantum critical point between Fermi-liquid and spin-liquid phases.

Observation of power-law divergence in spin susceptibility within the spin-liquid phase.

Evidence of a low-temperature instability leading to a possible ordered phase.

Abstract

We study analytically the Kondo lattice model with an additional nearest-neighbor antiferromagnetic interaction in the framework of large-N theory. We find that there is a local quantum critical point between two phases, a normal Fermi-liquid and a spin-liquid in which the spins are decoupled from the conduction electrons. The local spin susceptibility displays a power-law divergence throughout the spin liquid phase. We check the reliability of the large-N results by solving by quantum Monte Carlo simulation the N=2 spin-liquid problem with no conduction electrons and find qualitative agreement. We show that the spin-liquid phase is unstable at low temperatures, suggestive of a first-order transition to an ordered phase.