Magnetism of magic-angle twisted bilayer graphene

Abstract

We investigate magnetic instabilities in charge-neutral twisted bilayer graphene close to so-called "magic angles" using a combination of real-space Hartree-Fock and dynamical mean-field theories. In view of the large size of the unit cell close to magic angles, we examine a previously proposed rescaling that permits to mimic the same underlying flat minibands at larger twist angles. We find that localized magnetic states emerge for values of the Coulomb interaction $U$ that are significantly smaller than what would be required to render an isolated layer antiferromagnetic. However, this effect is overestimated in the rescaled system, hinting at a complex interplay of flatness of the minibands close to the Fermi level and the spatial extent of the corresponding localized states. Our findings shed new light on perspectives for experimental realization of magnetic states in charge-neutral twisted bilayer graphene.

arXiv comment23 pages including 7 multi-panel figures; published version

References in corpus (63)

• Electric Field Effect in Atomically Thin Carbon Films
• The electronic properties of graphene
• Magic-angle graphene superlattices: a new platform for unconventional superconductivity
• 2D materials and van der Waals heterostructures
• Correlated Insulator Behaviour at Half-Filling in Magic Angle Graphene Superlattices
• Moire bands in twisted double-layer graphene
• Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene
• Graphene bilayer with a twist: electronic structure
• The numerical renormalization group method for quantum impurity systems
• Emergence of magnetism in graphene materials and nanostructures
• Magic Angle Spectroscopy
• Flat Bands in Slightly Twisted Bilayer Graphene
• Graphene Bilayers with a Twist
• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Localization of Dirac electrons by Moire patterns in graphene bilayers
• Imaging Electronic Correlations in Twisted Bilayer Graphene near the Magic Angle
• Charge-Order and Broken Rotational Symmetry in Magic Angle Twisted Bilayer Graphene
• Spectroscopic signatures of many-body correlations in magic angle twisted bilayer graphene
• Continuum Model of the Twisted Bilayer
• Origin of Mott insulating behavior and superconductivity in twisted bilayer graphene
• Maximally-localized Wannier orbitals and the extended Hubbard model for the twisted bilayer graphene
• Optical Absorption in Twisted Bilayer Graphene
• Colloquium: Spintronics in graphene and other two-dimensional materials
• Strong coupling phases of partially filled twisted bilayer graphene narrow bands
• Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice
• Symmetry, maximally localized Wannier states, and low energy model for the twisted bilayer graphene narrow bands
• Numerical studies of confined states in rotated bilayers of graphene
• Ground State and Hidden Symmetry of Magic Angle Graphene at Even Integer Filling
• Chiral SDW and d + id superconductivity in the magic-angle twisted bilayer-graphene
• Pinning the order: the nature of quantum criticality in the Hubbard model on honeycomb lattice
• Twisted Bilayer Graphene IV. Exact Insulator Ground States and Phase Diagram
• Unconventional superconductivity in nearly flat bands in twisted bilayer graphene
• Twisted bilayer graphene III. Interacting Hamiltonian and exact symmetries
• Theories for the correlated insulating states and quantum anomalous Hall phenomena in twisted bilayer graphene
• Electronic spectrum of twisted graphene layers under heterostrain
• Electrically controllable magnetism in twisted bilayer graphene
• Possible correlated insulating states in magic-angle twisted bilayer graphene under strongly competing interactions
• Correlated insulating phases of twisted bilayer graphene at commensurate filling fractions: a Hartree-Fock study
• Twisted bilayer graphene. II. Stable symmetry anomaly
• Twisted Bilayer Graphene V: Exact Analytic Many-Body Excitations in Twisted Bilayer Graphene Coulomb Hamiltonians: Charge Gap, Goldstone Modes and Absence of Cooper Pairing
• Band structure and insulating states driven by the Coulomb interaction in twisted bilayer graphene
• Dynamical Signatures of Edge-State Magnetism on Graphene Nanoribbons
• Magnetism of Finite Graphene Samples: Mean-Field Theory compared with Exact Diagonalization and Quantum Monte Carlo Simulation
• Twisted bilayer graphene.VI. An Exact Diagonalization Study of Twisted Bilayer Graphene at Non-Zero Integer Fillings
• Twisted bilayer graphene I. Matrix elements, approximations, perturbation theory and a $k\cdot p$ 2-Band model
• Interplay of Fractional Chern Insulator and Charge-Density-Wave Phases in Twisted Bilayer Graphene
• Correlation-induced insulating topological phases at charge neutrality in twisted bilayer graphene
• Exact Diagonalization for Magic-Angle Twisted Bilayer Graphene
• Heterostrain rules the flat-bands in magic-angle twisted graphene layers
• The nature of correlations in the insulating states of twisted bilayer graphene
• The Hubbard model on the honeycomb lattice: from static and dynamical mean-field theories to lattice quantum Monte Carlo simulations
• Absence of spin liquid in non-frustrated correlated systems
• Spin Density Waves in the Hubbard model - A DMFT approach
• Flat-band ferromagnetism in twisted bilayer graphene
• Large and Small Fermi-Surface Spin Density Waves in the Kondo Lattice Model
• Importance of long-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene
• Inherited and flatband-induced ordering in twisted graphene bilayers
• Functional renormalization group for a large moiré unit cell
• Multiband Dual Fermion Approach to Quantum Criticality in the Hubbard Honeycomb Lattice
• Spin-caloritronic transport in hexagonal graphene nanoflakes
• Magnetic phases from competing Hubbard and extended Coulomb interactions in twisted bilayer graphene
• Chiral $p$-wave superconductivity in twisted bilayer graphene from dynamical mean field theory
• Antiferromagnetism and chiral d-wave superconductivity from an effective $t-J-D$ model for twisted bilayer graphene