Topological Mixed Valence Model in Magic-Angle Twisted Bilayer Graphene

TL;DR

This paper introduces a topological mixed valence model for magic-angle twisted bilayer graphene, revealing novel mixed-valence properties and insights into unconventional superconductivity using a heavy-fermion framework.

Contribution

It develops a new theoretical model employing a large-N slave-boson approach to describe mixed valence in MATBG, highlighting differences from traditional heavy-fermion systems.

Findings

Reveals novel mixed-valence properties in MATBG

Provides a mean-field solution near Mott insulator regime

Suggests microscopic origins for unconventional superconductivity

Abstract

We develop a model to describe the mixed valence regime in magic-angle twisted bilayer graphene (MATBG) using the recently developed heavy-fermion framework. By employing the large-$N$ slave-boson approach, we derive the self-consistent mean field equations and solve them numerically. We find that the SU(8) symmetry constraint moir\'e system exhibits novel mixed-valence properties which are different from conventional heavy-fermions systems. We find the solutions describing the physics at the filling near the Mott insulator regime in the limit of strong Coulomb interactions between the flat-band fermions. Our model can provide additional insight into the possible microscopic origin of unconventional superconductivity in MATBG.