Fig. 2
Device SEM image and fan diagram for the 2DEG. a Scanning electron microscope (SEM) micrograph of the studied device, which is fabricated in a 2DEG embedded in a GaAs/AlGaAs double-quantum well structure. It consists of the upper (light purple), center (brown), and lower (light purple) regions, and the density in each region can be independently controlled by its own top gate, with voltages Vg1, Vg2, and Vg3. A few ohmic contacts are located at the interfaces between two regions (dark yellow squares) and others located away to measure the generalized fillings of the three regions (dark serrated yellow squares). Each source (S) is placed in-between two drains (D) in order to measure two-terminal conductance. b 2D mapping of the longitudinal resistance, RXX, versus magnetic field and gate voltage Vg1 at T = 20 mK. Data are obtained from the ohmic contacts along the edge of the upper region, in a quantum well with 0.7 -nm-thick AlAs barrier, with the adjacent region pinched off. c The zoom-in on the “interesting” region used in our work. The white and red dashed lines represent the non-interacting spin-split Landau levels—LL2 in SB1 and LL1 in SB2, respectively. The field Bc describes the magnetic field where non-interacting subbands cross and hybridize. The clear vertical square (containing the yellow dashed lines) illustrates the region in magnetic field where a transition between the generalized fillings of v = (1,1) and v = (4/3,0) can be tuned
