The breakdown of the mean-field description of the Nagaoka phase

Abstract

We discuss the relevance of the improved mean-field slave-fermion theory to describe the Nagaoka ($U=\infty$) limit of the Hubbard model. In this theory the crucial on-site constraint of no double electron occupancy is taken into account rigorously prior to the mean-field approximation. At one-loop approximation the effective mean-field action shows a long-range ferromagnetic order over the whole doping range. This indicates that the slave-fermion mean-field theory does not constitute an appropriate framework to describe the physics of the Nagaoka phase. We discuss the drawbacks of this mean-field theory and present some results on the derivation of a low-energy effective spin action to describe the Nagaoka phase beyond the mean-field approximation.

10 pages, revised and extended version. To be published in Phys. Rev. B

References in corpus (4)

• The cold atom Hubbard toolbox
• A dynamical mean-field theory study of Nagaoka ferromagnetism
• Resonating Valence Bond Theory of Superconductivity for Dopant Carriers: Application to the Cobaltates
• Limitations of the mean field slave-particle approximations

Cited by in corpus (3)

• Effective action for strongly correlated electron systems
• Breakdown of the Nagaoka phase at finite doping
• Stability of Nagaoka phase, spin effective action and delocalized free holes