Photoluminescence of PbS nanocrystals at high magnetic fields up to 30 T

We use magnetic fields up to 30 T to study the circularly polarized magneto-photoluminescence (PL) of colloidal PbS nanocrystals. A semiclassical model for the population of polarized excitons is used to account for the measured magnetic field and temperature dependence of the degree of circular polarization of the PL emission and to probe the g factor, g_X , of the exciton. We report a systematic dependence of g_X on the nanocrystal size with values that increase from 0.1 to 0.3 at low temperature (T<10K) with decreasing the nanocrystal diameter from 9 to 4 nm.