The paper discusses the unconventional quantum Hall effect (QHE) observed in bilayer graphene, which is characterized by charge carriers with a parabolic energy spectrum but chiral behavior and Berry's phase of 2π. This results in a unique set of Hall conductivity plateaus, where the zero-level plateau is missing, and the conductivity exhibits metallic behavior at low concentrations and high magnetic fields. The authors explain that the chiral fermions in bilayer graphene arise from the coupling between two graphene layers, transforming massless Dirac fermions into chiral quasiparticles. These quasiparticles have a parabolic spectrum and accumulate a Berry's phase of 2π along their cyclotron trajectories. The study reveals that the two lowest Landau levels in bilayer graphene are exactly at zero energy, leading to the missing plateau and a double-step behavior in the Hall conductivity. The experimental results are compared with theoretical predictions, highlighting the distinct properties of bilayer graphene's QHE compared to conventional systems.The paper discusses the unconventional quantum Hall effect (QHE) observed in bilayer graphene, which is characterized by charge carriers with a parabolic energy spectrum but chiral behavior and Berry's phase of 2π. This results in a unique set of Hall conductivity plateaus, where the zero-level plateau is missing, and the conductivity exhibits metallic behavior at low concentrations and high magnetic fields. The authors explain that the chiral fermions in bilayer graphene arise from the coupling between two graphene layers, transforming massless Dirac fermions into chiral quasiparticles. These quasiparticles have a parabolic spectrum and accumulate a Berry's phase of 2π along their cyclotron trajectories. The study reveals that the two lowest Landau levels in bilayer graphene are exactly at zero energy, leading to the missing plateau and a double-step behavior in the Hall conductivity. The experimental results are compared with theoretical predictions, highlighting the distinct properties of bilayer graphene's QHE compared to conventional systems.