OSCILLATIONS OF THE SPECTRUM OF ACOUSTIC PHONONS INTERACTING WITH COMPOSITE FERMIONS

The interaction of collective excitations in a composite fermion syste m with phonon modes is considered. It is shown that for parameters cor responding to real systems in which the fractional quantum Hall effect is observed, the phase velocity of acoustic phonons has an oscillatin g dependence on the wave vector. The obtained oscillating structure of the phonon spectrum is determined to a considerable extent by the ext ernal magnetic field and electron concentration. (C) 1997 American Ins titute of Physics. [S1063-777X(97)01312-1].