Slave rotor theory of antiferromagnetic Hubbard model

TL;DR

This paper extends the slave-rotor mean-field theory to analyze the antiferromagnetic phase of the Hubbard model, revealing a crossover to an incoherent phase in the spectral function not captured by Hartree-Fock theory.

Contribution

It generalizes the slave-rotor approach to include antiferromagnetism and derives an effective action to study the phase diagram and spectral properties.

Findings

Magnetic phase persists for all U values.

Spectral function shows a crossover to incoherence within a specific magnetic moment window.

Deviation from Hartree-Fock predictions in the spectral behavior.

Abstract

The slave-rotor mean-field theory of Florens and Georges is generalized to the antiferromagnetic phase of the Hubbard model. An effective action consisting of a spin rotor and a fermion is derived and the corresponding saddle-point action is analyzed. Zero-temperature phase diagram of the antiferromagnetic Hubbard model is presented. While the magnetic phase persists for all values of the Hubbard interaction U, the single-particle spectral function exhibits a crossover into an incoherent phase when the magnetic moment m (and the corresponding U values) lies within a certain window m_c < m < 1-m_c, indicating a possible deviation from the Hartree-Fock theory.