Magneto-optical effects observed for GaSe in megagauss magnetic fields

Abstract

Magnetoabsorption spectra of a layered compound GaSe have been measured both for the Faraday and for the Voigt configurations with magnetic fields up to 150 T. Interband transitions between the Landau subbands have been clearly observed for the Faraday configuration. The exciton exhibited a diamagnetic shift, from which we estimated the reduced mass of the exciton, ${\ensuremath{\mu}}_{\ensuremath{\perp}}=0.15$ and ${\ensuremath{\mu}}_{\ensuremath{\Vert}}=0.13.$ The anisotropy of the reduced mass is surprisingly small in spite of the layered structure of the crystal. We have also observed the anticrossing effect between the $2s$ and the ${3d}_{0}$ states of the hydrogen-atom-like excitonic states. We discussed the correspondence between the excitonic states in a relatively low magnetic field and the Landau states in a high magnetic field.