Exciton absorption spectra of a highly anisotropic crystal GaTe in a magnetic field

We have measured optical-absorption spectra of thin GaTe single crystals in a magnetic field at 2 K. Three kinds of excitons are observed in the $n=1$ exciton energy region. In the Voigt configuration, we have observed one and two components for E∥b and E⊥b polarizations, respectively in the $n=1$ and 2 exciton lines. These magnetic behaviors cannot be interpreted on the basis of the LS coupling regime. An analysis is proposed to explain the origin of the three types of excitons from the viewpoint of j-j coupling. Our model calculation well explains the Zeeman splitting and the diamagnetic shift of the exciton peak energies.