Spin Liquid States at the vicinity of metal-insulator transition

TL;DR

This paper develops a phenomenological Landau-like theory for quantum spin liquids near the metal-insulator transition, proposing an alternative to the Brinkman-Rice picture and analyzing their charge, spin, and thermal responses.

Contribution

It introduces a new low energy theoretical framework for QSLs near the transition, linking spinon excitations to Fermi surface structures and expanding understanding of Mott transitions.

Findings

U(1) QSLs are a key example within the proposed class of spin liquids.

The theory offers an alternative perspective to the Brinkman-Rice picture.

Charge, spin, and thermal responses of QSLs are characterized within this framework.

Abstract

We study in this paper quantum spin liquid states (QSLs) at the vicinity of metal-insulator transition. Assuming that the low energy excitations in the QSLs are labeled by "spinon" occupation numbers with the same Fermi surface structure as in the corresponding metal (Fermi-liquid) side, we propose a phenomenological Landau-like low energy theory for the QSLs and show that the usual U(1) QSLs is a representative member of this class of spin liquids. Based on our effective low energy theory, an alternative picture to the Brinkman-Rice picture of Mott metal-insulator transition is proposed. The charge, spin and thermal responses of QSLs are discussed under such a phenomenology.