COLLECTIVE CYCLOTRON MODES IN HIGH-MOBILITY 2-DIMENSIONAL HOLE SYSTEMS IN GAAS-(GA,AL)AS HETEROJUNCTIONS .2. EXPERIMENTS AT MAGNETIC-FIELDSOF UP TO FORTY TESLA

The cyclotron resonance of very high-mobility holes in GaAs-(Ga,Al)As heterojunctions grown on (111), (311) and (100) substrates has been st udied in high magnetic fields of up to 40 T. As the temperature is inc reased from similar to 4 K to similar to 20 K, the cyclotron resonance is found to shift to lower magnetic fields, the size of shift dependi ng on the cyclotron frequency and the substrate orientation. These obs ervations may be explained using the model of interacting hole subsyst ems developed by Cole et al.