Fig. 4: Anomalous behavior of Landau levels in BZ minibands.

a High-resolution σ_xx (V_g, B) for the hole-doped region marked in Fig. 1c (device D1). The measurements below B = 12.5 T were carried out at 10 mK, and at 250 mK in the fields above. B was applied in steps of 16 and 40 mT above and below 12.5 T, respectively, except for the low left corner where the data were acquired at higher resolution of 10 mT (seen as discontinuities in the contrast). Log scale: indigo (310 nS) to yellow (0.3 mS). b Schematics for the conductance minima found in (a). The same color coding as in Fig. 3b. The solid lines indicate LLs evolving as expected, linearly in B and V_g. The thin curves indicate the anomalous bending whereas the dotted curves show the staircase-like evolution observed for some LLs. All the anomalous features were highly reproducible and, for example, did not depend on the step size in B.