Fig. 4. First-order orbital phase transitions at the high field for D < 0.

a, b Landau fan diagram of ρ_xx (a) and ρ_xy (b) for device D2 at D = −0.37 V/nm, acquired at T = 0.1 K. c Schematic representation of the observed states, following the convention established in Fig. 3. A subset of the most robust gapped states we observe are labeled by their respective (t, s) indices. States at all integer t are observed for s = 0 and 1, indicating full degeneracy lifting. d ρ_xx acquired as B is swept back and forth at ν = 2.00 (left) and ν = 3.04 (right). e ρ_yx acquired as B is swept back and forth at ν = 3.16 (left), ν = 3.22 (middle), and ν = 3.27 (right). Data in (d, e) are acquired at T = 0.1 K.