Spin-Orbital Density Wave and a Mott Insulator in a Two-Orbital Hubbard Model on a Honeycomb Lattice

Abstract

Inspired by recent discovery of correlated insulating states in twisted bilayer graphene (TBG), we study a two-orbital Hubbard model on the honeycomb lattice with two electrons per unit cell. Based on the real-space density matrix renormalization group (DMRG) simulation, we identify a metal-insulator transition around $U_c/t=2.5\sim 3$. In the vicinity of $U_c$, we find strong spin/orbital density wave fluctuations at commensurate wavevectors, accompanied by weaker incommensurate charge density wave (CDW) fluctuations. The spin/orbital density wave fluctuations are enhanced with increasing system sizes, suggesting the possible emergence of long-range order in the two dimensional limit. At larger $U$, our calculations indicate a possible nonmagnetic Mott insulator phase without spin or orbital polarization. Our findings offer new insights into correlated electron phenomena in twisted bilayer graphene and other multi-orbital honeycomb materials.

arXiv comment6 pages, 6 figures

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Cited by in corpus (9)

• Is magic-angle twisted bilayer graphene near a quantum critical point?
• Fractional quantum Hall states for moiré superstructures in the Hofstadter regime
• Correlated Insulating Phases in the Twisted Bilayer Graphene
• $\mathrm{SU}(4)$-Symmetric Quantum Spin-Orbital Liquids on Various Lattices
• Extended Metal-Insulator Crossover with Strong Antiferromagnetic Spin Correlation in Half-Filled 3D Hubbard Model
• Obstruction and Interference in Low Energy Models for Twisted Bilayer Graphene
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• Gutzwiller approximation approach to the SU(4) $t$-$J$ model
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