Emergent Massless Dirac Fermions in Moiré Bands of Bilayer Graphene/hBN Superlattice

A superlattice of multilayer graphene and hBN has proven to be a promising pathway for engineering electronic band structures and topologies. In this work, we experimentally demonstrate the role of hBN alignment in inducing topological band reconstruction in bilayer graphene (BLG) superlattices. Our study establishes that while the primary band retains its massive chiral nature, the secondary bands host massless, chiral fermions. Magnetotransport measurements, including Quantum Hall, temperature-dependent Shubnikov-de Haas oscillations, and Berry phase analysis, confirm the distinct topological nature of these bands. A significantly reduced Fermi velocity (vF ≈ 3.6 × 10 ^5 ms^-1) in the moiré secondary band indicates band flattening induced by the moiré potential. Our study provides a pathway for controlling topological quantum transport in BLG/hBN superlattices.