U(1) Gauge Theory of the Hubbard Model : Spin Liquid States and Possible Application to k-(BEDT-TTF)_2 Cu_2 (CN)_3

TL;DR

This paper develops a U(1) gauge theory for the Hubbard model using the slave-rotor approach, suggesting the existence of spin liquid phases near the Mott transition, with implications for organic materials like k-(BEDT-TTF)_2 Cu_2 (CN)_3.

Contribution

It introduces a U(1) gauge theoretical framework for the Hubbard model and proposes spin liquid states near the Mott transition on specific lattices.

Findings

Spin liquid phases may exist near the Mott transition.

Organic compound k-(BEDT-TTF)_2 Cu_2 (CN)_3 is a candidate for spin liquid behavior.

Predicted unusual temperature dependence of thermal conductivity.

Abstract

We formulate a U(1) gauge theory of the Hubbard model in the slave-rotor representation. From this formalism it is argued that spin liquid phases may exist near the Mott transition in the Hubbard model on triangular and honeycomb lattices at half filling. The organic compound k-(BEDT-TTF)_2 Cu_2 (CN)_3 is a good candidate for the spin liquid state on a triangular lattice. We predict a highly unusual temperature dependence for the thermal conductivity of this material.