Fig2d_data.mat contains all the data to generate Fig.2d

 Vg [V] is the accumulation gate
 Hall_density [cm^-2] is the density extracted from low field Hall effect
 FFT_density1 [cm^-2] and FFT_density2 [cm^-2] are the two valleys density extrapolated from the FFT
 FFT_density_tot [cm^-2] is the total density extrapolated from FFT
 FFT_density_delta [cm^-2] is the density difference extrapolated from FFT