Topological Insulator — Surface Dirac Cone

3D TI surface states: spin-momentum locking and topological protection
H_surf = ℏv_F(k_x σ_y − k_y σ_x) + m·σ_z  |  E = ±√(v_F²k² + m²)
1.0
0.00
0.50
1.0
Dirac point energy
0
Fermi wavevector k_F
Chern number Z2