Correlation stabilized anomalous Hall crystal in bilayer graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Interacting electrons at low carrier densities can form a Wigner crystal.
• Rhombohedral multilayer graphene exhibits high-order Dirac fermions with nontrivial Berry phases.

Purpose of the Study:

• Investigate ground states of charge-doped rhombohedral multilayer graphene under vertical displacement field.
• Explore the transition between Fermi liquid and Wigner crystal phases.
• Identify conditions for the emergence of an anomalous Hall crystal.

Main Methods:

• Utilized a beyond-mean-field theoretical framework.
• Studied electron interactions in rhombohedral multilayer graphene.
• Analyzed ground state properties under varying displacement fields and dielectric constants.

Main Results:

• Observed a Fermi liquid to trivial Wigner crystal transition at ~1-2 × 10^11 cm^-2.
• Discovered an anomalous Hall crystal phase at lower densities (~2 × 10^10 cm^-2) for dielectric constants ϵr ≲ 5.
• Found the anomalous Hall crystal is stabilized by lower correlation energy from dynamical charge fluctuations.

Conclusions:

• Rhombohedral bilayer graphene is a promising candidate for realizing the anomalous Hall crystal.
• The theoretical framework is applicable to other interacting 2D systems, including moiré superlattices.