Magneto-optical effects of excitons inBiI3crystals under pulsed high magnetic fields: Indirect and direct excitons

Magneto-optical spectra for the exciton transitions near the fundamental absorption edge in ${\mathrm{BiI}}_3$ crystals were investigated in pulsed high magnetic fields up to 42 T. A remarkable anisotropy was observed in the magneto-optical effects on both the indirect and direct excitons with respect to the relative direction of magnetic field and incident light polarization. It was found that both the energy shift of all the observed excitons and the intensity of field-induced excitons showed a quadratic dependence on magnetic field. The observed magnetic-field effects were interpreted in terms of the characteristic Zeeman effects on small-radius cationic excitons including the 6${\mathit{s}}^2$-to-6s6p transitions in the cations.