Intrinsic Layer Polarization and Multi-flatband Transport in Non-centrosymmetric Mixed-Stacked Multilayer Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Graphene multilayers show electronic properties sensitive to layer number and stacking.
• Non-centrosymmetric stacking orders in multilayer graphene are less explored but promise unique electronic behaviors.

Purpose of the Study:

• Investigate the electronic properties of ABCBC-stacked pentalayer graphene.
• Explore the interplay of symmetry breaking, flatbands, and quantum phenomena in this material.

Main Methods:

• Fabrication and characterization of ABCBC-stacked pentalayer graphene.
• Transport measurements under varying perpendicular displacement fields and carrier densities.
• Analysis of Landau level degeneracies and quantum Hall states.

Main Results:

• Observed an intrinsic gap at charge neutrality that evolves asymmetrically with displacement field, indicating built-in layer polarization.
• Drove multiple Lifshitz transitions and identified Landau levels from a multi-flatband structure.
• Discovered a novel quantum Hall state (ν = -6) at a low magnetic field of ~20 mT.

Conclusions:

• ABCBC-stacked pentalayer graphene is a tunable platform for exploring non-centrosymmetric physics.
• The coexistence of flatbands and broken symmetries facilitates unusual quantum Hall effects.
• This material opens opportunities for studying emergent correlated and topological electronic states.