Fig. 4: Interlayer exciton phase diagram.

a Scatter plot of linewidth vs. electron-hole density for various trap depths at T = 4 K. The error bars indicate the uncertainty of the fittings. The black dashed line shows the exponential fit giving a universal critical density \({n}_{{eh}}^{*}\)(4 K) = 1.30( ± 0.09)×10¹²cm⁻². Inset: Same data but where linewidth is on a log scale and density on linear scaling, showing the exponential fit is shown as a linear curve. b, c Same as (a) but at 30 K with \({n}_{{eh}}^{*}\)(30 K) = 1.37( ± 0.06)×10¹²cm⁻² and 50 K with \({n}_{{eh}}^{*}\)(50 K) = 1.77( ± 0.32)× 10¹²cm⁻², respectively. d Plot of the fitted normalized linewidth over the collected data range as a function of pair density and measured temperature. The blue data shows the extracted \({n}_{{eh}}^{*}\)(T) at different temperatures with the error bars showing the uncertainty of the fits. The red dashed line is the degeneracy temperature, T_D as a function of exciton density per flavor.