Fig. 1

Kerr rotation at the heavy hole neutral donor transiton. a Normalized PL spectrum of the studied sample. Red line is the laser spectrum. Sketch on the left represents the level scheme of total energy states for the single electron ground state D⁰ (thin green arrow) and an excited state composed from a two-electron singlet state and a heavy hole (thick black arrow). B _x is the applied magnetic field, and σ^± indicates the circularly polarized laser excitation with corresponding selection rules. b Normalized Kerr rotation signal measured for resonant D⁰X-HH excitation at B _x  = 34 mT for two pump powers, 0.3 and 10 mW. Gray dashed line is a fit to the high power data. c Spectral dependence of the normalized Kerr rotation amplitude at −50 ps delay for 0.3 mW (blue) and for 10 mW (red). T = 1.8 K