Spin polarized nematic order, quantum valley Hall states, and field tunable topological transitions in twisted multilayer graphene systems

Abstract

We theoretically study the correlated insulator states, quantum anomalous Hall (QAH) states, and field-induced topological transitions between different correlated states in twisted multilayer graphene systems. Taking twisted bilayer-monolayer graphene and twisted double-bilayer graphene as examples, we show that both systems stay in spin polarized, $C_{3z}$-broken insulator states with zero Chern number at 1/2 filling of the flat bands under finite displacement fields. In some cases these spin polarized, nematic insulator states are in the quantum valley Hall phase by virtue of the nontrivial band topology of the systems. The spin polarized insulator state is quasi-degenerate with the valley polarized state if only the dominant intra-valley Coulomb interaction is included. Such quasi-degeneracy can be split by atomic on-site interactions such that the spin polarized, nematic state become the unique ground state. Such a scenario applies to various twisted multilayer graphene systems at 1/2 filling, thus can be considered as a universal mechanism. Moreover, under vertical magnetic fields, the orbital Zeeman splittings and the field-induced change of charge density in twisted multilayer graphene systems would compete with the atomic Hubbard interactions, which can drive transitions from spin polarized zero-Chern-number states to valley-polarized QAH states with small onset magnetic fields.

5+19 pages

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Cited by in corpus (18)

• Topological charge density waves at half-integer filling of a moiré superlattice
• Heavy fermion representation for twisted bilayer graphene systems
• Tunable moiré materials for probing Berry physics and topology
• Exact Many-Body Ground States from Decomposition of Ideal Higher Chern Bands: Applications to Chirally Twisted Graphene Multilayers
• Theory of fractional Chern insulator states in pentalayer graphene moiré superlattice
• Isospin competitions and valley polarized correlated insulators in twisted double bilayer graphene
• Correlated insulators, density wave states, and their nonlinear optical response in magic-angle twisted bilayer graphene
• Molecular Pairing in Twisted Bilayer Graphene Superconductivity
• Spectroscopic visualization of flat bands in magic-angle twisted monolayer-bilayer graphene: localization-delocalization coexisting electronic states
• Alternating twisted mutilayer graphene: generic partition rules, double flat bands, and orbital magnetoelectric effect
• Colossal orbital Zeeman effect driven by tunable spin-Berry curvature in a kagome metal
• Synergistic correlated states and nontrivial topology in coupled graphene-insulator heterostructures
• Electron phonon coupling in the topological heavy fermion model of twisted bilayer graphene
• Observation of first-order quantum phase transitions and ferromagnetism in twisted double bilayer graphene
• Nonlinear optical responses and quantum geometry in rhombohedral trilayer graphene
• Hybrid-Order Topological Phase And Transition in 1H Transition Metal Compounds
• General Many-Body Perturbation Framework for Moiré Systems
• Three-dimensional flat bands and possible interlayer triplet pairing superconductivity in the alternating twisted NbSe${}_2$ moiré bulk