Onset of charge incompressibility and Mott gaps in the Honeycomb-Lattice SU(4) Hubbard Model: Lessons for Twisted Bilayer Graphene systems

Abstract

We use finite temperature strong coupling expansions to calculate thermodynamic properties of the Honeycomb-lattice SU(4) Hubbard model. We present numerical results for various properties including chemical potential, compressibility, entropy and specific heat as a function of temperature and density at several $U/t$ values. We study the onset of charge incompressibility and Mott gaps as the temperature is lowered at integer densities. In the incompressible Mott regime, the expansions are recast into a high temperature expansion for a generalized spin model with SU(4) symmetry, which is then used to study the convergence of strong coupling expansions in t/U. We discuss lessons that can be drawn from high temperature properties of a simple Hubbard model regarding Twisted Bilayer Graphene (TBG) and other magic-angle flat-band systems.

6 pages, 6 figures

References in corpus (10)

• Ultracold fermions and the SU(N) Hubbard model
• Entropic evidence for a Pomeranchuk effect in magic angle graphene
• Numerical Linked-Cluster Approach to Quantum Lattice Models
• Effective spin model for the spin-liquid phase of the Hubbard model on the triangular lattice
• SU(4) chiral spin liquid, exciton supersolid and electric detection in moiré bilayers
• Spectroscopy Signatures of Electron Correlations in a Trilayer Graphene/hBN Moiré Superlattice
• Neel order, ring exchange and charge fluctuations in the half-filled Hubbard model
• Universal thermodynamics of an SU($N$) Fermi-Hubbard Model
• Rigorous results on the ground state of the attractive SU($N$) Hubbard model
• Finite Temperature Strong Coupling Expansions for the SU(N) Hubbard Model