GRAPHENE DIRAC CONE
Massless Dirac fermions at K and K' points
t (hopping, eV)
2.7
Mass gap Δ (eV)
0.00
Fermi energy E_F (eV)
0.0
B field (T)
0
VIEW
3D Band
Lattice
Landau Levels
OBSERVABLES
v_F (m/s)
~10⁶
Topology
Berry π
Half-int QHE
σ = ±(n+½)e²/h
H = ℏv_F(σ_x k_x + σ_y k_y) + Δσ_z
Graphene's honeycomb lattice yields linear band crossings at K, K' with Fermi velocity v_F ≈ 10⁶ m/s (c/300). Berry phase π gives anomalous QHE: σ_xy = (n+½)e²/h. A gap Δ breaks inversion symmetry.