Generalizing Quantum Hall Ferromagnetism to Fractional Chern Bands

Abstract

We study the interplay between quantum Hall ordering and spontaneous sublattice symmetry breaking in multiple Chern number bands at fractional fillings. Primarily we study fermions with repulsive interactions near half filling in a family of square lattice models with flat C=2 bands and a wide band gap. By perturbing about the particularly transparent limit of two decoupled C=1 bands and by exact diagonalization studies of small systems in the more general case, we show that the system generically breaks sublattice symmetry with a transition temperature $T_c>0$ and additionally exhibits a quantized Hall conductance of $e^2/h$ as $T\to 0$. We note the close analogy to quantum Hall ferromagnetism in the multi-component problem and the connection to topological Mott insulators. We also discuss generalizations to other fillings and higher Chern numbers.

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Cited by in corpus (12)

• Observation of fractional Chern insulators in a van der Waals heterostructure
• Topological charge density waves at half-integer filling of a moiré superlattice
• Topological Flat Bands and Correlated States in Twisted Monolayer-Bilayer Graphene
• Recent Developments in Fractional Chern Insulators
• Domain wall competition in the Chern insulating regime of twisted bilayer graphene
• Two-component quantum Hall effects in topological flat bands
• Flat-band ferromagnetism in a topological Hubbard model
• Tuning the topological insulator states of artificial graphene
• Symmetry breaking and fermionic fractional Chern insulator in topologically trivial bands
• Symmetry-broken Chern insulators in twisted double bilayer graphene
• Quantum Hall effects of exciton condensate in topological flat bands
• Higher Chern bands in helical homotrilayer transition metal dichalcogenides