Fig. 5: The effective mass term.

Band structure of pristine TBG with different mass terms. a Δb = 30 meV and Δt = 0, b Δb = Δt = 30 meV, c Δb = −Δt = 30 meV and d Δb = 30 meV and Δt = −40 meV. In each panel, blue and red lines are the bands corresponding to each valley. The periodic potentials are set to zero.