Fig. 2.

Zeeman splitting and non-equilibrium distribution of biexciton emission. a A strong out-of-plane magnetic field splits most emission peaks into pairs. The splitting of XX is similar to that of the X⁰ feature (g-factor 4.4 ± 0.5), whereas the splitting of the X^D feature is larger because of its non-zero spin. b The ratios of amplitudes of the fitted low-energy branch (LEB) and high-energy branch (HEB) of the emission spectra. Unlike the X^D pair, the XX emission pair exhibits inverted populations between the HEB and LEB. The LEB/HEB ratio of the XX pair is similar to that of X⁰/X^D. The error bars for X⁰, X^D, and XX are conservative estimates. c A diagram of the biexciton intervalley configuration as probed through the PL measurements in a magnetic field. The B-field splits the bright (light blue) and dark (dark blue) exciton into pairs according to their valley index (K, K′). Analysis of the PL intensities shows that the biexciton is composed of excitons from different valleys