Magneto-Optical Properties of Highly Anisotropic Holes in HgTe/CdTe Superlattices

Far-infrared magneto-optical experiments have been performed on a $p$-type HgTe/CdTe superlattice with a small effective band gap. The angular dependence of the hole-cyclotron-resonance spectra reveals that the effective mass is 2 orders of magnitude heavier in the growth direction than transverse to it. These results provide evidence for a large valence-band offset. In addition, a tentative identification of hole spin resonance has been made. Evidence is presented which shows that the superlattice band structure can be substantially modified by the application of modest magnetic fields.