Dirac points, spinons and spin liquid in twisted bilayer graphene

TL;DR

This paper explores the complex electronic and magnetic phases of twisted bilayer graphene, focusing on Dirac points, spinons, and the potential spin liquid state, using advanced theoretical models.

Contribution

It introduces a novel analysis of Dirac points via spinon Fermi surfaces and applies gauge field theory to describe the deconfined spin liquid phase in twisted bilayer graphene.

Findings

Identification of spinon Fermi surface in strongly correlated regime

Application of gauge field theory to spin liquid phase

Discussion of topological quantum transitions involving Fermi surface changes

Abstract

Twisted bilayer graphene is an excellent example of highly correlated system demonstrating a nearly flat electron band, the Mott transition and probably a spin liquid state. Besides the one-electron picture, analysis of Dirac points is performed in terms of spinon Fermi surface in the limit of strong correlations. Application of gauge field theory to describe deconfined spin liquid phase is treated. Topological quantum transitions, including those from small to large Fermi surface in the presence of van Hove singularities, are discussed.