Inversion-asymmetry-induced magnetooptical transitions in HgTe/CdTe superlattices

A new far-infrared magnetooptical transition, much weaker than the cyclotron resonance of the conduction electrons is observed for the first time in an n-type HgTe/CdTe superlattice. The photon energy for the new transition is about twice the energy of the cyclotron resonance at a given magnetic field. A theoretical calculation of the transition intensities points out that this new weak transition is induced by the inversion asymmetry of the bulk HgTe and CdTe materials. Other aspects of the theoretical results also agree well with the experiment. The results lead to the conclusion that the valence-band offset at a HgTe/CdTe heterojunction is less than 70 meV.