Extended Data Fig. 7: DFT calculated band structure of 6SL MnBi₂Te₄.

a, Band structure of 6SL MnBi₂Te₄ in k_y direction. b, DFT calculated band contours at specific energies (0.05 eV and 0.10 eV), marked with dashed lines in panel (a). The low energy Dirac bands show dramatic asymmetry between + k_y and − k_y. c, DFT calculated nonlinear conductivity σ^2ω as a function of Fermi level E_f. We obtained the relaxation time τ = 2.1 × 10⁻¹⁴ s based on the Drude conductivity. We note that our calculations are based on the DFT band structure of 6SL MnBi₂Te₄, which predicts a magnetic gap ~ 50 meV. However, experimentally, the gap size is not settled^37,40. In particular, spatial inhomogeneity can smear out the magnetic gap⁴⁴. Moreover, the antisite defects could suppress the band gap and can increase the quantum metric effect, as predicted in Ref. ³².